House Sparrow

House Sparrow| Passer domesticus

Printed in March 2009, this print of a female House sparrow was created using enamel paint on paper.

House sparrow info via Wikipedia

House sparrow
Passer domesticus male (15).jpg
Male in Germany
House Sparrow, England - May 09.jpg
Female in England
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Family: Passeridae
Genus: Passer
Species: P. domesticus
Binomial name
Passer domesticus
(Linnaeus, 1758)
PasserDomesticusDistribution.png
   Native range
   Introduced range
Synonyms[2]

Fringilla domestica Linnaeus, 1758
Passer domesticus (Linnaeus, 1758) Brisson, 1760
Pyrgita domestica (Linnaeus, 1758) G. Cuvier, 1817
Passer indicus Jardine and Selby, 1835
Passer arboreus Bonaparte, 1850 (preoccupied)
Passer confucius Bonaparte, 1853
Passer rufidorsalis C. L. Brehm, 1855
Passer engimaticus Zarudny, 1903
Passer ahasvar Kleinschmidt, 1904

The house sparrow (Passer domesticus) is a bird of the sparrow family Passeridae, found in most parts of the world. A small bird, it has a typical length of 16 cm (6.3 in) and a mass of 24–39.5 g (0.85–1.39 oz). Females and young birds are coloured pale brown and grey, and males have brighter black, white, and brown markings. One of about 25 species in the genus Passer, the house sparrow is native to most of Europe, the Mediterranean Basin, and much of Asia. Its intentional or accidental introductions to many regions, including parts of Australia, Africa, and the Americas, make it the most widely distributed wild bird.

The house sparrow is strongly associated with human habitations, and can live in urban or rural settings. Though found in widely varied habitats and climates, it typically avoids extensive woodlands, grasslands, and deserts away from human development. It feeds mostly on the seeds of grains and weeds, but it is an opportunistic eater and commonly eats insects and many other foods. Its predators include domestic cats, hawks, owls, and many other predatory birds and mammals.

Because of its numbers, ubiquity, and association with human settlements, the house sparrow is culturally prominent. It is extensively, and usually unsuccessfully, persecuted as an agricultural pest. It has also often been kept as a pet, as well as being a food item and a symbol of lust, sexual potency, commonness, and vulgarity. Though it is widespread and abundant, its numbers have declined in some areas. The animal's conservation status is listed as least concern on the IUCN Red List.

Description

Measurements and shape

The house sparrow is typically about 16 cm (6.3 in) long, ranging from 14 to 18 cm (5.5 to 7.1 in).[3] It is a compact bird with a full chest and a large, rounded head. Its bill is stout and conical with a culmen length of 1.1–1.5 cm (0.43–0.59 in), strongly built as an adaptation for eating seeds. Its tail is short, at 5.2–6.5 cm (2.0–2.6 in) long. The wing chord is 6.7–8.9 cm (2.6–3.5 in), and the tarsus is 1.6–2.5 cm (0.63–0.98 in).[4][5] In mass, the house sparrow ranges from 24 to 39.5 g (0.85 to 1.39 oz). Females usually are slightly smaller than males. The median mass on the European continent for both sexes is about 30 g (1.1 oz), and in more southerly subspecies is around 26 g (0.92 oz). Younger birds are smaller, males are larger during the winter, and females are larger during the breeding season.[6] Birds at higher latitudes, colder climates, and sometimes higher altitudes are larger (under Bergmann's rule), both between and within subspecies.[6][7][8][9]

Plumage

Male house sparrows in breeding (left) and nonbreeding (right) plumage

The plumage of the house sparrow is mostly different shades of grey and brown. The sexes exhibit strong dimorphism: the female is mostly buffish above and below, while the male has boldly coloured head markings, a reddish back, and grey underparts.[8] The male has a dark grey crown from the top of its bill to its back, and chestnut brown flanking its crown on the sides of its head. It has black around its bill, on its throat, and on the spaces between its bill and eyes (lores). It has a small white stripe between the lores and crown and small white spots immediately behind the eyes (postoculars), with black patches below and above them. The underparts are pale grey or white, as are the cheeks, ear coverts, and stripes at the base of the head. The upper back and mantle are a warm brown, with broad black streaks, while the lower back, rump and uppertail coverts are greyish brown.[10]

Plumage of female house sparrow

The male is duller in fresh nonbreeding plumage, with whitish tips on many feathers. Wear and preening expose many of the bright brown and black markings, including most of the black throat and chest patch, called the "bib" or "badge".[10][11] The badge is variable in width and general size, and may signal social status or fitness. This hypothesis has led to a "veritable 'cottage industry'" of studies, which have only conclusively shown that patches increase in size with age.[12] The male's bill is black in the breeding season and horn (dark grey) during the rest of the year.[3]

A close-up of a male house sparrow's head

The female has no black markings or grey crown. Its upperparts and head are brown with darker streaks around the mantle and a distinct pale supercilium. Its underparts are pale grey-brown. The female's bill is brownish-grey and becomes darker in breeding plumage approaching the black of the male's bill.[3][10]

Juveniles are similar to the adult female, but deeper brown below and paler above, with paler and less defined supercilia. Juveniles have broader buff feather edges, and tend to have looser, scruffier plumage, like moulting adults. Juvenile males tend to have darker throats and white postoculars like adult males, while juvenile females tend to have white throats. However, juveniles cannot be reliably sexed by plumage: some juvenile males lack any markings of the adult male, and some juvenile females have male features. The bills of young birds are light yellow to straw, paler than the female's bill. Immature males have paler versions of the adult male's markings, which can be very indistinct in fresh plumage. By their first breeding season, young birds generally are indistinguishable from other adults, though they may still be paler during their first year.[3][10]

Voice

A male calling in San Francisco
Calls, recorded in England

Most house sparrow vocalisations are variations on its short and incessant chirping call. Transcribed as chirrup, tschilp, or philip, this note is made as a contact call by flocking or resting birds, or by males to proclaim nest ownership and invite pairing. In the breeding season, the male gives this call repetitively, with emphasis and speed, but not much rhythm, forming what is described either as a song or an "ecstatic call" similar to a song.[13][14] Young birds also give a true song, especially in captivity, a warbling similar to that of the European greenfinch.[15]

Aggressive males give a trilled version of their call, transcribed as "chur-chur-r-r-it-it-it-it". This call is also used by females in the breeding season, to establish dominance over males while displacing them to feed young or incubate eggs.[16] House sparrows give a nasal alarm call, the basic sound of which is transcribed as quer, and a shrill chree call in great distress.[17] Another vocalisation is the "appeasement call", a soft quee given to inhibit aggression, usually given between birds of a mated pair.[16] These vocalisations are not unique to the house sparrow, but are shared, with small variations, by all sparrows.[18]

Variation

A male of subspecies P. d. indicus in Kolkata, India
A male of subspecies P. d. parkini at Rajkot, India

Some variation is seen in the 12 subspecies of house sparrows, which are divided into two groups, the Oriental P. d. indicus group, and the Palaearctic P. d. domesticus group. Birds of the P. d. domesticus group have grey cheeks, while P. d. indicus group birds have white cheeks, as well as bright colouration on the crown, a smaller bill, and a longer black bib.[19] The subspecies P. d. tingitanus differs little from the nominate subspecies, except in the worn breeding plumage of the male, in which the head is speckled with black and underparts are paler.[20]P. d. balearoibericus is slightly paler than the nominate, but darker than P. d. bibilicus.[21]P. d. bibilicus is paler than most subspecies, but has the grey cheeks of P. d. domesticus group birds. The similar P. d. persicus is paler and smaller, and P. d. niloticus is nearly identical but smaller.[20] Of the less widespread P. d. indicus group subspecies, P. d. hyrcanus is larger than P. d. indicus, P. d. hufufae is paler, P. d. bactrianus is larger and paler, and P. d. parkini is larger and darker with more black on the breast than any other subspecies.[20][22][23]

Identification

The house sparrow can be confused with a number of other seed-eating birds, especially its relatives in the genus Passer. Many of these relatives are smaller, with an appearance that is neater or "cuter", as with the Dead Sea sparrow.[24] The dull-coloured female can often not be distinguished from other females, and is nearly identical to those of the Spanish and Italian sparrows.[10] The Eurasian tree sparrow is smaller and more slender with a chestnut crown and a black patch on each cheek.[25] The male Spanish sparrow and Italian sparrow are distinguished by their chestnut crowns. The Sind sparrow is very similar but smaller, with less black on the male's throat and a distinct pale supercilium on the female.[10]

Taxonomy and systematics

Names

The house sparrow was among the first animals to be given a scientific name in the modern system of biological classification, since it was described by Carl Linnaeus, in the 1758 10th edition of Systema Naturae. It was described from a type specimen collected in Sweden, with the name Fringilla domestica.[26][27] Later, the genus name Fringilla came to be used only for the common chaffinch and its relatives, and the house sparrow has usually been placed in the genus Passer created by French zoologist Mathurin Jacques Brisson in 1760.[28][29]

The bird's scientific name and its usual English name have the same meaning. The Latin word passer, like the English word "sparrow", is a term for small active birds, coming from a root word referring to speed.[30][31] The Latin word domesticus means "belonging to the house", like the common name a reference to its association with humans.[32] The house sparrow is also called by a number of alternative English names, including English sparrow, chiefly in North America;[33][34] and Indian sparrow or Indian house sparrow, for the birds of the Indian subcontinent and Central Asia.[35] Dialectal names include sparr, sparrer, spadger, spadgick, and philip, mainly in southern England; spug and spuggy, mainly in northern England; spur and sprig, mainly in Scotland;[36][37] and spatzie or spotsie, from the German Spatz, in North America.[38]

Taxonomy

A pair of Italian sparrows, in Rome

The genus Passer contains about 25 species, depending on the authority, 26 according to the Handbook of the Birds of the World.[39] Most Passer species are dull-coloured birds with short, square tails and stubby, conical beaks, between 11 and 18 cm (4.3 and 7.1 in) long.[8][40]Mitochondrial DNA studies suggest that speciation in the genus occurred during the Pleistocene and earlier, while other evidence suggests speciation occurred 25,000 to 15,000 years ago.[41][42] Within Passer, the house sparrow is part of the "Palaearctic black-bibbed sparrows" group and a close relative of the Mediterranean "willow sparrows".[39][43]

The taxonomy of the house sparrow and its Mediterranean relatives is highly complicated. The common type of "willow sparrow" is the Spanish sparrow, which resembles the house sparrow in many respects.[44] It frequently prefers wetter habitats than the house sparrow, and it is often colonial and nomadic.[45] In most of the Mediterranean, one or both species occur, with some degree of hybridisation.[46] In North Africa, the two species hybridise extensively, forming highly variable mixed populations with a full range of characters from pure house sparrows to pure Spanish sparrows.[47][48][49]

In much of Italy, a form apparently intermediate between the house and Spanish sparrows, is known as the Italian sparrow. It resembles a hybrid between the two species, and is in other respects intermediate. Its specific status and origin are the subject of much debate.[48][50] In the Alps, the Italian sparrow intergrades over a roughly 20 km (12 mi) strip with the house sparrow,[51] but to the south it intergrades over the southern half of Italy and some Mediterranean islands with the Spanish sparrow.[48] On the Mediterranean islands of Malta, Gozo, Crete, Rhodes, and Karpathos, the other apparently intermediate birds are of unknown status.[48][52][53]

Subspecies

A male of subspecies P. d. balearoibericus in Istanbul
A male of the migratory subspecies P. d. bactrianus (with a Eurasian tree sparrow and young house or Spanish sparrows) in Baikonur, Kazakhstan

A large number of subspecies have been named, of which 12 were recognised in the Handbook of the Birds of the World. These subspecies are divided into two groups, the Palaearctic P. d. domesticus group, and the Oriental P. d. indicus group.[39] Several Middle Eastern subspecies, including P. d. biblicus, are sometimes considered a third, intermediate group. The subspecies P. d. indicus was described as a species, and was considered to be distinct by many ornithologists during the 19th century.[19]

Migratory birds of the subspecies P. d. bactrianus in the P. d. indicus group were recorded overlapping with P. d. domesticus birds without hybridising in the 1970s, so the Soviet scientists Edward I. Gavrilov and M. N. Korelov proposed the separation of the P. d. indicus group as a separate species.[28][54] However, P. d. indicus-group and P. d. domesticus-group birds intergrade in a large part of Iran, so this split is rarely recognised.[39]

In North America, house sparrow populations are more differentiated than those in Europe.[7] This variation follows predictable patterns, with birds at higher latitudes being larger and those in arid areas being paler.[8][55][56] However, how much this is caused by evolution or by environment is not clear.[57][58][59][60] Similar observations have been made in New Zealand,[61] and in South Africa.[62] The introduced house sparrow populations may be distinct enough to merit subspecies status, especially in North America and southern Africa,[39] and American ornithologist Harry Church Oberholser even gave the subspecies name P. d. plecticus to the paler birds of western North America.[55]

P. d. domesticus group
P. d. indicus group
  • P. d. hyrcanus Zarudny and Kudashev, 1916, described from Gorgan, Iran, is found along the southern coast of the Caspian Sea from Gorgan to south-eastern Azerbaijan. It intergrades with P. d. persicus in the Alborz mountains, and with P. d. bibilicus to the west. It is the subspecies with the smallest range.[39][63]
  • P. d. bactrianus Zarudny and Kudashev, 1916, described from Tashkent, is found in southern Kazakhstan to the Tian Shan and northern Iran and Afghanistan. It intergrades with persicus in Baluchistan and with indicus across central Afghanistan. Unlike most other house sparrow subspecies, it is almost entirely migratory, wintering in the plains of the northern Indian subcontinent. It is found in open country rather than in settlements, which are occupied by the Eurasian tree sparrow in its range.[39][63] There is an exceptional record from Sudan.[64]
  • P. d. parkini Whistler, 1920, described from Srinagar, Kashmir, is found in the western Himalayas from the Pamir Mountains to south-eastern Nepal. It is migratory, like P. d. bactrianus.[19][63]
  • P. d. indicus Jardine and Selby, 1831, described from Bangalore, is found in the Indian subcontinent south of the Himalayas, in Sri Lanka, western Southeast Asia, eastern Iran, south-western Arabia and southern Israel.[19][39][63]
  • P. d. hufufae Ticehurst and Cheeseman, 1924, described from Hofuf in Saudi Arabia, is found in north-eastern Arabia.[63][66]
  • P. d. rufidorsalis C. L. Brehm, 1855, described from Khartoum, Sudan, is found in the Nile valley from Wadi Halfa south to Renk in northern South Sudan,[63][64] and in eastern Sudan, northern Ethiopia to the Red Sea coast in Eritrea.[39] It has also been introduced to Mohéli in the Comoros.[67]

Distribution and habitat

By a nest in a saguaro cactus in Arizona
House sparrows perching on a roof, during winter in the Southern Alps of New Zealand

The house sparrow originated in the Middle East and spread, along with agriculture, to most of Eurasia and parts of North Africa.[68] Since the mid-19th century, it has reached most of the world, chiefly due to deliberate introductions, but also through natural and shipborne dispersal.[69] Its introduced range encompasses most of North America, Central America, southern South America, southern Africa, part of West Africa, Australia, New Zealand, and islands throughout the world.[70] It has greatly extended its range in northern Eurasia since the 1850s,[71] and continues to do so, as was shown by the colonisations around 1990 of Iceland and Rishiri Island, Japan.[72] The extent of its range makes it the most widely distributed wild bird on the planet.[70]

Introductions

The house sparrow has become highly successful in most parts of the world where it has been introduced. This is mostly due to its early adaptation to living with humans, and its adaptability to a wide range of conditions.[73][74] Other factors may include its robust immune response, compared to the Eurasian tree sparrow.[75] Where introduced, it can extend its range quickly, sometimes at a rate over 230 km (140 mi) per year.[76] In many parts of the world, it has been characterised as a pest, and poses a threat to native birds.[77][78] A few introductions have died out or been of limited success, such as those to Greenland and Cape Verde.[79]

The first of many successful introductions to North America occurred when birds from England were released in New York City, in 1852 [80][81] to control the ravages of the linden moth.[82] The house sparrow now occurs from the Northwest Territories to southern Panama,[4] and it is one of the most abundant birds in North America.[77] The house sparrow was first introduced to Australia in 1863 at Melbourne and is common throughout the eastern part of the continent,[79] but has been prevented from establishing itself in Western Australia, where every house sparrow found in the state is killed.[83] House sparrows were introduced in New Zealand in 1859, and from there reached many of the Pacific islands, including Hawaii.[84]

In southern Africa, birds of both the European subspecies P. d. domesticus and the Indian subspecies P. d. indicus were introduced around 1900. Birds of P. d. domesticus ancestry are confined to a few towns, while P. d. indicus birds have spread rapidly, reaching Tanzania in the 1980s. Despite this success, native relatives such as the Cape sparrow also occur in towns, competing successfully with it.[79][85] In South America, it was first introduced near Buenos Aires around 1870, and quickly became common in most of the southern part of the continent. It now occurs almost continuously from Tierra del Fuego to the fringes of the Amazon basin, with isolated populations as far north as coastal Venezuela.[79][86][87]

Habitat

The house sparrow is closely associated with human habitation and cultivation.[88] It is not an obligate commensal of humans as some have suggested: Central Asian house sparrows usually breed away from humans in open country,[89] and birds elsewhere are occasionally found away from humans.[88][90][91] The only terrestrial habitats that the house sparrow does not inhabit are dense forest and tundra. Well adapted to living around humans, it frequently lives and even breeds indoors, especially in factories, warehouses, and zoos.[88] It has been recorded breeding in an English coal mine 640 m (2,100 ft) below ground,[92] and feeding on the Empire State Building's observation deck at night.[93] It reaches its greatest densities in urban centres, but its reproductive success is greater in suburbs, where insects are more abundant.[88][94] On a larger scale, it is most abundant in wheat-growing areas such as the Midwestern United States.[95]

It tolerates a variety of climates, but prefers drier conditions, especially in moist tropical climates.[79][88] It has several adaptations to dry areas, including a high salt tolerance[96] and an ability to survive without water by ingesting berries.[97] In most of eastern Asia, the house sparrow is entirely absent, replaced by the Eurasian tree sparrow.[98] Where these two species overlap, the house sparrow is usually more common than the Eurasian tree sparrow, but one species may replace the other in a manner that ornithologist Maud Doria Haviland described as "random, or even capricious".[99] In most of its range, the house sparrow is extremely common, despite some declines,[100] but in marginal habitats such as rainforest or mountain ranges, its distribution can be spotty.[88]

Behaviour

The house sparrow often bathes in water (at left) or in dust (at right)

Social behaviour

The house sparrow is a very social bird. It is gregarious at all seasons when feeding, often forming flocks with other types of birds.[101] It roosts communally, its nests are usually grouped together in clumps, and it engages in social activities such as dust or water bathing and "social singing", in which birds call together in bushes.[102][103] The house sparrow feeds mostly on the ground, but it flocks in trees and bushes.[102] At feeding stations and nests, female house sparrows are dominant despite their smaller size, and in the reproductive period (usually spring or summer), being dominant, they can fight for males.[104][105]

Sleep and roosting

House sparrows sleep with the bill tucked underneath the scapular feathers.[106] Outside of the reproductive season, they often roost communally in trees or shrubs. Much communal chirping occurs before and after the birds settle in the roost in the evening, as well as before the birds leave the roost in the morning.[102] Some congregating sites separate from the roost may be visited by the birds prior to settling in for the night.[107]

Body maintenance

Dust or water bathing is common and often occurs in groups. Anting is rare.[108] Head scratching is done with the leg over the drooped wing.[107]

Feeding

Female foraging in Germany
Two females feeding on leftover food at a cafe in New Zealand.

As an adult, the house sparrow mostly feeds on the seeds of grains and weeds, but it is opportunistic and adaptable, and eats whatever foods are available.[109] In towns and cities, it often scavenges for food in garbage containers and congregates in the outdoors of restaurants and other eating establishments to feed on leftover food and crumbs. It can perform complex tasks to obtain food, such as opening automatic doors to enter supermarkets,[110] clinging to hotel walls to watch vacationers on their balconies,[111] and nectar robbing kowhai flowers.[112] In common with many other birds, the house sparrow requires grit to digest the harder items in its diet. Grit can be either stone, often grains of masonry, or the shells of eggs or snails; oblong and rough grains are preferred.[113][114]

Several studies of the house sparrow in temperate agricultural areas have found the proportion of seeds in its diet to be about 90%.[109][115][116] It will eat almost any seeds, but where it has a choice, it prefers oats and wheat.[117] In urban areas, the house sparrow feeds largely on food provided directly or indirectly by humans, such as bread, though it prefers raw seeds.[116][118] The house sparrow also eats some plant matter besides seeds, including buds, berries, and fruits such as grapes and cherries.[97][116] In temperate areas, the house sparrow has an unusual habit of tearing flowers, especially yellow ones, in the spring.[119]

Animals form another important part of the house sparrow's diet, chiefly insects, of which beetles, caterpillars, dipteran flies, and aphids are especially important. Various noninsect arthropods are eaten, as are molluscs and crustaceans where available, earthworms, and even vertebrates such as lizards and frogs.[109] Young house sparrows are fed mostly on insects until about 15 days after hatching.[120] They are also given small quantities of seeds, spiders, and grit. In most places, grasshoppers and crickets are the most abundant foods of nestlings.[121]True bugs, ants, sawflies, and beetles are also important, but house sparrows take advantage of whatever foods are abundant to feed their young.[121][122][123] House sparrows have been observed stealing prey from other birds, including American robins.[4]

Locomotion

The house sparrow's flight is direct (not undulating) and flapping, averaging 45.5 km/h (28.3 mph) and about 15 wingbeats per second.[107][124] On the ground, the house sparrow typically hops rather than walks. It can swim when pressed to do so by pursuit from predators. Captive birds have been recorded diving and swimming short distances under water.[107]

Dispersal and migration

Most house sparrows do not move more than a few kilometres during their lifetimes. However, limited migration occurs in all regions. Some young birds disperse long distances, especially on coasts, and mountain birds move to lower elevations in winter.[102][125][126] Two subspecies, P. d. bactrianus and P. d. parkini, are predominantly migratory. Unlike the birds in sedentary populations that migrate, birds of migratory subspecies prepare for migration by putting on weight.[102]

Breeding

A pair of the subspecies P. d. indicus mating in Kolkata

House sparrows can breed in the breeding season immediately following their hatching, and sometimes attempt to do so. Some birds breeding for the first time in tropical areas are only a few months old and still have juvenile plumage.[127] Birds breeding for the first time are rarely successful in raising young, and reproductive success increases with age, as older birds breed earlier in the breeding season, and fledge more young.[128] As the breeding season approaches, hormone releases trigger enormous increases in the size of the sexual organs and changes in day length lead males to start calling by nesting sites.[129][130] The timing of mating and egg-laying varies geographically, and between specific locations and years because a sufficient supply of insects is needed for egg formation and feeding nestlings.[131]

Males take up nesting sites before the breeding season, by frequently calling beside them. Unmated males start nest construction and call particularly frequently to attract females. When a female approaches a male during this period, the male displays by moving up and down while drooping and shivering his wings, pushing up his head, raising and spreading his tail, and showing his bib.[131] Males may try to mate with females while calling or displaying. In response, a female will adopt a threatening posture and attack a male before flying away, pursued by the male. The male displays in front of her, attracting other males, which also pursue and display to the female. This group display usually does not immediately result in copulations.[131] Other males usually do not copulate with the female.[132][133] Copulation is typically initiated by the female giving a soft dee-dee-dee call to the male. Birds of a pair copulate frequently until the female is laying eggs, and the male mounts the female repeatedly each time a pair mates.[131]

The house sparrow is monogamous, and typically mates for life. Birds from pairs often engage in extra-pair copulations, so about 15% of house sparrow fledglings are unrelated to their mother's mate.[134] Male house sparrows guard their mates carefully to avoid being cuckolded, and most extra-pair copulation occurs away from nest sites.[132][135] Males may sometimes have multiple mates, and bigamy is mostly limited by aggression between females.[136] Many birds do not find a nest and a mate, and instead may serve as helpers around the nest for mated pairs, a role which increases the chances of being chosen to replace a lost mate. Lost mates of both sexes can be replaced quickly during the breeding season.[132][137] The formation of a pair and the bond between the two birds is tied to the holding of a nest site, though paired house sparrows can recognise each other away from the nest.[131]

Nesting

Female bringing food for young in a nest made in a tree hole in California

Nest sites are varied, though cavities are preferred. Nests are most frequently built in the eaves and other crevices of houses. Holes in cliffs and banks, or tree hollows, are also used.[138][139] A sparrow sometimes excavates its own nests in sandy banks or rotten branches, but more frequently uses the nests of other birds such as those of swallows in banks and cliffs, and old tree cavity nests.[138] It usually uses deserted nests, though sometimes it usurps active ones.[138][140] Tree hollows are more commonly used in North America than in Europe,[138] putting the sparrows in competition with bluebirds and other North American cavity nesters, and thereby contributing to their population declines.[77]

Especially in warmer areas, the house sparrow may build its nests in the open, on the branches of trees, especially evergreens and hawthorns, or in the nests of large birds such as storks or magpies.[131][138][141] In open nesting sites, breeding success tends to be lower, since breeding begins late and the nest can easily be destroyed or damaged by storms.[138][142] Less common nesting sites include street lights and neon signs, favoured for their warmth; and the old open-topped nests of other songbirds, which are then domed over.[138][139]

The nest is usually domed, though it may lack a roof in enclosed sites.[138] It has an outer layer of stems and roots, a middle layer of dead grass and leaves, and a lining of feathers, as well as of paper and other soft materials.[139] Nests typically have external dimensions of 20 × 30 cm (8 × 12 in),[131] but their size varies greatly.[139] The building of the nest is initiated by the unmated male while displaying to females. The female assists in building, but is less active than the male.[138] Some nest building occurs throughout the year, especially after moult in autumn. In colder areas house sparrows build specially created roost nests, or roost in street lights, to avoid losing heat during the winter.[138][143] House sparrows do not hold territories, but they defend their nests aggressively against intruders of the same sex.[138]

House sparrows' nests support a wide range of scavenging insects, including nest flies such as Neottiophilum praestum, Protocalliphora blowflies,[144][145] and over 1,400 species of beetle.[146]

Eggs and young

Eggs in a nest

Clutches usually comprise four or five eggs, though numbers from one to 10 have been recorded. At least two clutches are usually laid, and up to seven a year may be laid in the tropics or four a year in temperate latitudes. When fewer clutches are laid in a year, especially at higher latitudes, the number of eggs per clutch is greater. Central Asian house sparrows, which migrate and have only one clutch a year, average 6.5 eggs in a clutch. Clutch size is also affected by environmental and seasonal conditions, female age, and breeding density.[147][148]

Naked and blind chick
A hatchling

Some intraspecific brood parasitism occurs, and instances of unusually large numbers of eggs in a nest may be the result of females laying eggs in the nests of their neighbours. Such foreign eggs are sometimes recognised and ejected by females.[147][149] The house sparrow is a victim of interspecific brood parasites, but only rarely, since it usually uses nests in holes too small for parasites to enter, and it feeds its young foods unsuitable for young parasites.[150][151] In turn, the house sparrow has once been recorded as a brood parasite of the American cliff swallow.[149][152]

A juvenile, showing its pink bill and obvious nestling gape—the soft, swollen base, which becomes harder and less swollen as the bird matures

The eggs are white, bluish white, or greenish white, spotted with brown or grey.[107] Subelliptical in shape,[8] they range from 20 to 22 mm (0.79 to 0.87 in) in length and 14 to 16 mm (0.55 to 0.63 in) in width,[4] have an average mass of 2.9 g (0.10 oz),[153] and an average surface area of 9.18 cm2 (1.423 in2).[154] Eggs from the tropical subspecies are distinctly smaller.[155][156] Eggs begin to develop with the deposition of yolk in the ovary a few days before ovulation. In the day between ovulation and laying, egg white forms, followed by eggshell.[157] Eggs laid later in a clutch are larger, as are those laid by larger females, and egg size is hereditary. Eggs decrease slightly in size from laying to hatching.[158] The yolk comprises 25% of the egg, the egg white 68%, and the shell 7%. Eggs are watery, being 79% liquid, and otherwise mostly protein.[159]

The female develops a brood patch of bare skin and plays the main part in incubating the eggs. The male helps, but can only cover the eggs rather than truly incubate them. The female spends the night incubating during this period, while the male roosts near the nest.[147] Eggs hatch at the same time, after a short incubation period lasting 11–14 days, and exceptionally for as many as 17 or as few as 9.[8][131][160] The length of the incubation period decreases as ambient temperature increases later in the breeding season.[161]

A female feeding a fledgling

Young house sparrows remain in the nest for 11 to 23 days, normally 14 to 16 days.[107][161][162] During this time, they are fed by both parents. As newly hatched house sparrows do not have sufficient insulation, they are brooded for a few days, or longer in cold conditions.[161][163] The parents swallow the droppings produced by the hatchlings during the first few days; later, the droppings are moved up to 20 m (66 ft) away from the nest.[163][164]

The chicks' eyes open after about four days and, at an age of about eight days, the young birds get their first down.[107][162] If both parents perish, the ensuing intensive begging sounds of the young often attract replacement parents which feed them until they can sustain themselves.[163][165] All the young in the nest leave it during the same period of a few hours. At this stage, they are normally able to fly. They start feeding themselves partly after one or two days, and sustain themselves completely after 7 to 10 days, 14 at the latest.[166]

Survival

In adult house sparrows, annual survival is 45–65%.[167] After fledging and leaving the care of their parents, young sparrows have a high mortality rate, which lessens as they grow older and more experienced. Only about 20–25% of birds hatched survive to their first breeding season.[168] The oldest known wild house sparrow lived for nearly two decades; it was found dead 19 years and 9 months after it was ringed in Denmark.[169] The oldest recorded captive house sparrow lived for 23 years.[170] The typical ratio of males to females in a population is uncertain due to problems in collecting data, but a very slight preponderance of males at all ages is usual.[171]

Predation

A male being eaten by a cat: Domestic cats are one of the main predators of the house sparrow.

The house sparrow's main predators are cats and birds of prey, but many other animals prey on them, including corvids, squirrels,[172] and even humans—the house sparrow has been consumed in the past by people in many parts of the world, and it still is in parts of the Mediterranean.[173] Most species of birds of prey have been recorded preying on the house sparrow in places where records are extensive. Accipiters and the merlin in particular are major predators, though cats are likely to have a greater impact on house sparrow populations.[172] The house sparrow is also a common victim of roadkill; on European roads, it is the bird most frequently found dead.[174]

Parasites and disease

The house sparrow is host to a huge number of parasites and diseases, and the effect of most is unknown. Ornithologist Ted R. Anderson listed thousands, noting that his list was incomplete.[175] The commonly recorded bacterial pathogens of the house sparrow are often those common in humans, and include Salmonella and Escherichia coli.[176]Salmonella is common in the house sparrow, and a comprehensive study of house sparrow disease found it in 13% of sparrows tested. Salmonella epidemics in the spring and winter can kill large numbers of sparrows.[175] The house sparrow hosts avian pox and avian malaria, which it has spread to the native forest birds of Hawaii.[177] Many of the diseases hosted by the house sparrow are also present in humans and domestic animals, for which the house sparrow acts as a reservoir host.[178]Arboviruses such as the West Nile virus, which most commonly infect insects and mammals, survive winters in temperate areas by going dormant in birds such as the house sparrow.[175][179] A few records indicate disease extirpating house sparrow populations, especially from Scottish islands, but this seems to be rare.[180]

The house sparrow is infested by a number of external parasites, which usually cause little harm to adult sparrows. In Europe, the most common mite found on sparrows is Proctophyllodes, the most common ticks are Argas reflexus and Ixodes arboricola, and the most common flea on the house sparrow is Ceratophyllus gallinae. A number of chewing lice occupy different niches on the house sparrow's body. Menacanthus lice occur across the house sparrow's body, where they feed on blood and feathers, while Brueelia lice feed on feathers and Philopterus fringillae occurs on the head.[144]

Physiology

House sparrows express strong circadian rhythms of activity in the laboratory. They were among the first bird species to be seriously studied in terms of their circadian activity and photoperiodism, in part because of their availability and adaptability in captivity, but also because they can "find their way" and remain rhythmic in constant darkness.[181][182] Such studies have found that the pineal gland is a central part of the house sparrow's circadian system: removal of the pineal eliminates the circadian rhythm of activity,[183] and transplant of the pineal into another individual confers to this individual the rhythm phase of the donor bird.[184] The suprachiasmatic nuclei of the hypothalamus have also been shown to be an important component of the circadian system of house sparrows.[185] The photoreceptors involved in the synchronisation of the circadian clock to the external light-dark cycle are located in the brain and can be stimulated by light reaching them directly though the skull, as revealed by experiments in which blind sparrows, which normally can still synchronise to the light-dark cycle, failed to do so once India ink was injected as a screen under the skin on top of their skulls.[186]

Similarly, even when blind, house sparrows continue to be photoperiodic, i.e. show reproductive development when the days are long, but not when the days are short. This response is stronger when the feathers on top of the head are plucked, and is eliminated when India ink is injected under the skin at the top of the head, showing that the photoreceptors involved in the photoperiodic response to day length are located inside the brain.[187]

House sparrows have also been used in studies of nonphotic entrainment (i.e. synchronisation to an external cycle other than light and dark): for example, in constant darkness, a situation in which the birds would normally reveal their endogenous, non-24-hour, "free-running" rhythms of activity, they instead show 24-hour periodicity if they are exposed to two hours of chirp playbacks every 24 hours, matching their daily activity onsets with the daily playback onsets.[188] House sparrows in constant dim light can also be entrained to a daily cycle based on the presence of food.[189] Finally, house sparrows in constant darkness can be entrained to a cycle of high and low temperature, but only if the difference between the two temperatures is large (38 versus 6 °C); some of the tested sparrows matched their activity to the warm phase, and others to the cold phase.[190]

Relationships with humans

Flocking and chirping together beneath a fluorescent tube light in Germany

The house sparrow is closely associated with humans. They are believed to have become associated with humans around 10,000 years ago. Subspecies P. d. bactrianus is least associated with humans and considered to be evolutionarily closer to the ancestral noncommensal populations.[191] Usually, it is regarded as a pest, since it consumes agricultural products and spreads disease to humans and their domestic animals.[192] Even birdwatchers often hold it in little regard because of its molestation of other birds.[77] In most of the world, the house sparrow is not protected by law. Attempts to control house sparrows include the trapping, poisoning, or shooting of adults; the destruction of their nests and eggs; or less directly, blocking nest holes and scaring off sparrows with noise, glue, or porcupine wire.[193] However, the house sparrow can be beneficial to humans, as well, especially by eating insect pests, and attempts at the large-scale control of the house sparrow have failed.[39]

The house sparrow has long been used as a food item. From around 1560 to at least the 19th century in northern Europe, earthenware "sparrow pots" were hung from eaves to attract nesting birds so the young could be readily harvested. Wild birds were trapped in nets in large numbers, and sparrow pie was a traditional dish, thought, because of the association of sparrows with lechery, to have aphrodisiac properties. Sparrows were also trapped as food for falconers' birds and zoo animals. In the early part of the 20th century, sparrow clubs culled many millions of birds and eggs in an attempt to control numbers of this perceived pest, but with only a localised impact on numbers.[194] House sparrows have been kept as pets at many times in history, though they have no bright plumage or attractive songs, and raising them is difficult.[195]

Status

The house sparrow has an extremely large range and population, and is not seriously threatened by human activities, so it is assessed as least concern for conservation on the IUCN Red List.[1] However, populations have been declining in many parts of the world.[196][197][198] These declines were first noticed in North America, where they were initially attributed to the spread of the house finch, but have been most severe in Western Europe.[199][200] Declines have not been universal, as no serious declines have been reported from Eastern Europe, but have even occurred in Australia, where the house sparrow was introduced recently.[201]

In Great Britain, populations peaked in the early 1970s,[202] but have since declined by 68% overall,[203] and about 90% in some regions.[204][205] In London, the house sparrow almost disappeared from the central city.[204] The numbers of house sparrows in the Netherlands have dropped in half since the 1980s,[94] so the house sparrow is even considered an endangered species.[206] This status came to widespread attention after a female house sparrow, referred to as the "Dominomus", was killed after knocking down dominoes arranged as part of an attempt to set a world record.[207] These declines are not unprecedented, as similar reductions in population occurred when the internal combustion engine replaced horses in the 1920s and a major source of food in the form of grain spillage was lost.[208][209]

Various causes for the dramatic decreases in population have been proposed, including predation, in particular by Eurasian sparrowhawks;[210][211][212] electromagnetic radiation from mobile phones;[213] and diseases.[214] A shortage of nesting sites caused by changes in urban building design is probably a factor, and conservation organisations have encouraged the use of special nest boxes for sparrows.[214][215][216][217] A primary cause of the decline seems to be an insufficient supply of insect food for nestling sparrows.[214][218] Declines in insect populations result from an increase of monoculture crops, the heavy use of pesticides,[219][220][221] the replacement of native plants in cities with introduced plants and parking areas,[222][223] and possibly the introduction of unleaded petrol, which produces toxic compounds such as methyl nitrite.[224]

Protecting insect habitats on farms,[225][226] and planting native plants in cities benefit the house sparrow, as does establishing urban green spaces.[227][228] To raise awareness of threats to the house sparrow, World Sparrow Day has been celebrated on 20 March across the world since 2010.[229] Over the recent years, the house sparrow population has been on the decline in many Asian countries, and this decline is quite evident in India. To promote the conservation of these birds, in 2012, the house sparrow was declared as the state bird of Delhi.[230]

Cultural associations

To many people across the world, the house sparrow is the most familiar wild animal and, because of its association with humans and familiarity, it is frequently used to represent the common and vulgar, or the lewd.[231] One of the reasons for the introduction of house sparrows throughout the world was their association with the European homeland of many immigrants.[81] Birds usually described later as sparrows are referred to in many works of ancient literature and religious texts in Europe and western Asia. These references may not always refer specifically to the house sparrow, or even to small, seed-eating birds, but later writers who were inspired by these texts often had the house sparrow in mind.[39][231][232] In particular, sparrows were associated by the ancient Greeks with Aphrodite, the goddess of love, due to their perceived lustfulness, an association echoed by later writers such as Chaucer and Shakespeare.[39][195][231][233] Jesus's use of "sparrows" as an example of divine providence in the Gospel of Matthew[234] also inspired later references, such as that in Shakespeare's Hamlet[231] and the Gospel hymn His Eye Is on the Sparrow.[235]

G37
The house sparrow is represented in ancient Egyptian art very rarely, but an Egyptian hieroglyph is based on it. The sparrow hieroglyph had no phonetic value and was used as a determinative in words to indicate small, narrow, or bad.[236] An alternative view is that the hieroglyph meant "a prolific man" or "the revolution of a year".[237]

See also

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  195. ^ a b Summers-Smith 2005, pp. 29–35
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  203. ^ "Sparrow numbers 'plummet by 68%'". BBC News. 20 November 2008. Retrieved 6 December 2009. 
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Works cited

External links

source: http://en.wikipedia.org/wiki/House_sparrow

Austin Art Board Submission

Would you like to see these inked animals on Billboards around Austin?

Urban Birds of Austin

Mexican Free-tailed Bat 1
Adam and I, coerced by our friend Hayley of the Biocreativity Blog, decided to enter into the Austin Art Board contest this year.  Only one submission per person, so Adam and I individually created a unique take on some of our prints.  I kept it simple, using the Mexican Freetail bat as my subject.  I thought it would be a nice specimen considering Austin’s love affair with this critter. Adam got a bit more creative, and did a  bit of a collage of a few birds, most of which we haven’t posted yet (we have tons of material coming soon).

 

 

 

Atlantic Needlefish

Atlantic Needlefish Gyotaku by Inked Animal
Atlantic Needlefish | Strongylura marina

Atlantic Needlefish Gyotaku by Inked Animal

 

Info via Wikipedia:

Strongylura marina
Fish4485 - Flickr - NOAA Photo Library.jpg
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Beloniformes
Family: Belonidae
Genus: Strongylura
Species: S. marina
Binomial name
Strongylura marina
(Walbaum, 1792)

Strongylura marina, known commonly as the Atlantic needlefish, is a common demersal needlefish species common in marinas and other areas with minimal current. Its extremely long jaw and body set this fish apart from other predators. Atlantic needlefish are found from Maine to Brazil and have been known to venture into freshwater for short periods.

Geographic range

Strongylura marina is found along western Atlantic coastal waters from Maine to southern Brazil, including areas along the coast of the Gulf of Mexico and Caribbean.[2][3] Atlantic needlefish are not restricted to ocean waters; they can be found in various estuaries and are capable of ascending well upstream into freshwater. S. marina is found in shallow waters throughout the Chesapeake Bay.[4] In Texas, S. marina is known to inhabit the following drainage units: Sabine Lake (including minor coastal drainages west to Galveston Bay), Galveston Bay (including minor coastal drainages west to mouth of Brazos River), Brazos River, Colorado River, San Antonio Bay (including minor coastal drainages west of mouth of Colorado River to mouth of Nueces River), Nueces River.[5]S. marina has also been introduced and now inhabits parts of the Tennessee River drainage throughout Alabama and Tennessee.[6]

Ecology

As juveniles, the diet of S. marina consists of 70% shrimp, mysids and amphipods and 30% fish, while adults are exclusively piscivorous.[7]

The predators of S. marina include larger piscivorous fish such as the Atlantic tarpon (Megalops atlanticus).[8] There are also less common predators that include S. marina in their diet such as the common bottlenose dolphin (Tursiops truncatus) and juvenile lemon sharks (Negaprion brevirostris).[9] Since they are surface swimmers, S. marina are also preyed upon by some birds. The competitors of S. marina include similar sized piscivorous fish species such as bonefish. Although the maximum salinity of Strongylura marina is 36.9 ppt,[8] they are able to adapt to a wide range of salinities, regularly venturing into fresh water.[3]

Life history

Spawning typically occurs in late spring and summer. In Texas, near ripe females have been reported in February.[8] Females lay eggs that have many long filamentous tendrils which attach to floating vegetation or other submerged objects and organisms. S. marina reaches reproductive maturity two years after being born. Spawning activity occurs in shallow inshore habitats with submerged algal masses.[2]

S. marina depends on submerged vegetation for breeding and shelter. In the Gulf of Mexico, the eggs of S. marina attach to sargassum seaweed.

Conservation

S. marina is not currently considered to be a threatened species. It is not of high commercial importance, but there is a fishery for it and it is sometimes taken as bycatch. Sport fishermen take it by angling and seining, and then use it as bait.[1]

Common names

Other common names for the fish include agujon, billfish, bluebone, garfish, green gar, harvest pike, northern needlefish, saltwater gar, sea pike, and silver gar.[1]

References

  1. ^ a b c Collen, B., et al. (Sampled Red List Index Coordinating Team) 2010. Strongylura marina. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. Downloaded on 06 June 2013.
  2. ^ a b Foster, N. R. 1974. Strongylura marina-Atlantic Needlefish. Manual for identification of early developmental stages of fishes of the Potomac River estuary. Environmental Technology Center, Marietta Corp., Baltimore, Md. 125-126.
  3. ^ a b Collette, B B. (1968). "Strongylura timucu (Wallbaum): A valid species of Western Atlantic needlefish". Copeia. 1968 (1): 189–192. JSTOR 1441578. doi:10.2307/1441578. 
  4. ^ Berry, F. H. & Rivas, L. R. (1962). "Data on six species of needlefishes (Belonidae) from the western Atlantic". Copeia. 1962: 152–160. JSTOR 1439490. doi:10.2307/1439490. 
  5. ^ Warren, M.L. Jr., B.M. Burr, S. J. Walsh, H.L. Bart Jr., R. C. Cashner, D.A. Etnier, B. J. Freeman, B.R. Kuhajda, R.L. Mayden, H. W. Robison, S.T. Ross & W. C. Starnes (2000). "Diversity, distribution and conservation status of the native freshwater fishes of the southern United States". Fisheries. 25: 7–29. doi:10.1577/1548-8446(2000)025<0007:DDACSO>2.0.CO;2. CS1 maint: Multiple names: authors list (link)
  6. ^ Boschung, H. T. (1992). "Catalogue of freshwater and marine fishes of Alabama". Alabama Museum of Natural History Bulletin. 14: 1–266. 
  7. ^ Carr, W. E. S. & Adam, C. A. (1973). "Food habits of juvenile marine fishes occupying seagrass beds in the estuarine zone near Crystal River, Florida". Transactions of the American Fisheries Society. 102: 511–540. doi:10.1577/1548-8659(1973)102<511:FHOJMF>2.0.CO;2. 
  8. ^ a b c Hardy, J. D, Jr. 1978. Development of fishes of the mid-Atlantic bight. Vol. II. Anguillidae through Syngnathidae. U.S. Fish and Wildlife Service, Biological Service Program: pp 458.
  9. ^ Gunter G. (1942). "Contributions to the natural history of the bottlenose dolphin, Tursiops truncatus (Montague), on the Texas coast, with particular reference to food habits". Journal of Mammalogy. 23: 267–276. doi:10.2307/1374993. 

External links

source: http://en.wikipedia.org/wiki/Strongylura_marina

Alligator Gar

Alligator Gar | Atractosteus spatula

 

We have to give some credit to Robby Maxwell here.  He aided with both the capture and immortalization of this beast.  It wasn’t the largest Alligator gar we’d seen, but large enough and a great time to catch. Robby, myself, and a large Texas State University crew wrangled this specimen as part of my master’s thesis working on the Brazos River watershed, Texas.  He’ll have to confirm, but I believe we caught this in the winter of 2008 in Brazos Bend State Park under the watchful gaze of park authority and many reptilian versions of alligators. This gyotaku print will surely be popular among many fish fanatics that I know who, justifiably so, respect the hell out of this fish. This species is known to get massive, one of the largest freshwater predators in the world.  Its even been featured on River Monsters I believe.  Its also a very old lineage of fish with a special version of a circulatory system that relies on oxygen brought in not just through its gills, but also through its toothy mug into its air bladder where gas exchange occurs.  For this reason, gar are one of those few fish that you can actually drown!


Alligator Gar info via Wikipedia:

Alligator gar
Alligator Gar 10.JPG
Alligator gar in an aquarium
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Family: Lepisosteidae
Genus: Atractosteus
Species: A. spatula
Binomial name
Atractosteus spatula
(Lacépède, 1803)
Atractosteus spatula range.png
Synonyms[1]

Alligator gar (Atractosteus spatula) are ray-finned euryhaline fish related to bowfin in the infraclass Holostei (ho'-las-te-i). The fossil record traces their existence to the Early Cretaceous over a hundred million years ago. They are the largest species in the gar family, and among the largest freshwater fishes in North America. Gars are often referred to as "primitive fishes", or "living fossils" because they have retained some morphological characteristics of their earliest ancestors, such as a spiral valve intestine which is also common to the digestive system of sharks, and the ability to breathe both air and water. Their common name was derived from their resemblance to American alligator, particularly their broad snout and long sharp teeth. Anecdotal evidence in several scientific reports suggest that an alligator gar can grow up to 10 ft (3.0 m) in length and weigh as much as 300 lb (140 kg); however in 2011 the largest alligator gar ever caught and officially recorded was 8 ft 5 14 in (2.572 m) long, weighed 327 lb (148 kg), and was 47 in (120 cm) around the girth.

The body of an alligator gar is torpedo shaped, usually brown or olive fading to a lighter gray or yellow ventral surface. Their scales are not like the scales of other fishes; rather, they are ganoid scales which are bone-like, diamond-shaped scales, often with serrated edges, and covered by an enamel-like substance. Ganoid scales are nearly impenetrable and are excellent protection against predation. Unlike other gar species, the upper jaw of an alligator gar has a dual row of large sharp teeth which are used to impale and hold prey. Alligator gar are stalking, ambush predators, primarily piscivores, but they will also ambush and eat water fowl and small mammals they find floating on the water's surface.

Populations of alligator gar have been extirpated from much of their historic range as a result of habitat destruction, indiscriminate culling, and unrestricted harvests. Populations are now located primarily in the southern portions of the United States extending into Mexico. They are considered euryhaline because they can adapt to varying salinities ranging from freshwater lakes and swamps to brackish marshes, estuaries, and bays along the Gulf of Mexico.

For nearly a half-century, alligator gar were considered "trash fish",[2] or a "nuisance species" detrimental to sport fisheries; therefore, were targeted for elimination by state and federal authorities in the United States. The 1980s brought a better understanding of the ecological balance necessary to sustain an ecosystem,[3] and eventually an awareness that alligator gar were no less important than any other living organism in the ecosystems they inhabit.[4] Over time, alligator gar were afforded some protection by state and federal resource agencies. They are also protected under the Lacey Act which makes it illegal to transport certain species of fish in interstate commerce when in violation of state law or regulation. Several state and federal resource agencies are monitoring populations in the wild, and have initiated outreach programs to educate the public. Alligator gar are being cultured in ponds, pools, raceways and tanks by federal hatcheries for mitigation stocking, by universities for research purposes, and in Mexico for consumption.[5]

Anatomy

Preserved display of an alligator gar head

Alligator gar are the largest species in the gar family, and among the largest freshwater fishes found in North America. Mature alligator gar commonly measure 6 ft (1.8 m) in length, and weigh over 100 lbs. (45 kg). However, anecdotal reports suggest they can grow up to 10 ft (3m) in length, and weigh as much as 350 lbs. (159 kg).[6] The largest alligator gar officially recorded was inadvertently caught in the net of fisherman Kenny Williams of Vicksburg, Mississippi while he was fishing the oxbow lakes of the Mississippi River on February 14, 2011. Williams was pulling up his net on Lake Chotard expecting to find buffalo fish, but instead discovered a large alligator gar tangled in his net. The gar was 8 ft 5 14 in (2.572 m) long, weighed 327 lb (148 kg), and its girth was 47 in (120 cm). According to wildlife officials, the fish was estimated to be somewhere between 50 and 70 years old; one report estimated the gar's age to be at least 95.[7] Williams donated it to the Mississippi Museum of Natural Science in Jackson where it will remain on display.[8][9]

Gill of a juvenile gar

All gars have torpedo-shaped bodies, but some distinguishing characteristics of adult alligator gar include their large size, heavy bodies, broad heads, short broad snouts, large sharp teeth and double row of teeth on their upper jaw. They are usually brown or olive fading to a lighter gray or yellow ventral surface. The dorsal and anal fins are positioned toward the back of their bodies, and their caudal fin is abbreviate-heterocercal, or non-symmetrical.[6]

Physiology

Alligator gar have gills, but unlike other species of fish, with few exceptions, they also have a highly vascularized swim bladder lung that supplements gill respiration.[10] The bladder not only provides buoyancy but also enables them to breathe in air which is why they are able to inhabit bodies of water in which most other fishes would die of suffocation. The swim bladder is connected to their foregut by a small pneumatic duct which allows them to breathe or gulp air when they break the surface,[11] an action that is seen quite frequently on lakes in the southern United States during the hot summer months. The scales of alligator gar are not like the scales of other fishes which have flexible elasmoid scales; their bodies are protected by inflexible and articulated ganoid scales that are diamond-shaped, often with serrated edges, and composed of a tough inner layer of bone and hard outer layer of ganoin which is essentially homologous to tooth enamel, making them nearly impenetrable.[12][13][14]

Taxonomy and evolution

Lacépède first described the alligator gar in 1803. The original name was Lepisosteus spatula, but was later changed by E.O. Wiley in 1976 to Atractosteus spatula in order to recognize two distinct extant taxon of gars. Synonyms of Atractosteus spatula include Lesisosteus [sic] ferox (Rafinesque 1820), and Lepisosteus spatula (Lacepede 1803). Fossils from the order Lepisosteiformes have been collected in Europe from the Cretaceous to Oligocene periods, in Africa and India from the Cretaceous, and in North America from the Cretaceous to recent times. Lepisosteidae is the only extant family of gar which has seven species all located in North and Central America.[6] The fossil record traces the existence of alligator gar back to the Early Cretaceous over a hundred million years ago.[15][16] Despite being a highly evolved species, alligator gar are often referred to as "primitive fishes", or "living fossils"[17][18] because they have retained a few morphological characteristics of their earliest ancestors with seemingly little to no apparent changes, such as a spiral valve intestine which is also common to the digestive system of sharks, an abbreviate-heterocercal tail, and a swim bladder lung for breathing in both air and water.[6][19][20]

Feeding behavior

Alligator gar are stalking, ambush predators

Alligator gar are relatively passive, seemingly sluggish solitary fish, but voracious ambush predators. They are opportunistic night predators and are primarily piscivores, but they will also ambush and eat water fowl and small mammals that may be floating on the surface. Their method of ambush is to float a few feet below the surface, and wait for unsuspecting prey to swim within reach. They lunge forward, and with a sweeping motion grab their prey, impaling it on their double rows of sharp teeth.[19]

Diet studies have shown alligator gar to be opportunistic piscivores, and even scavengers depending on the availability of their preferred food source. They occasionally ingest sport fish, but the majority of stomach content studies suggest they feed predominately on forage fishes such as gizzard shad as well as invertebrates, and water fowl. Diet studies have also revealed fishing tackle and boat engine parts in their stomachs.[21][22]

Spawning

As with most ancestral species, alligator gar are long living, and sexually late maturing. Most females do not reach sexual maturity until after their first decade of life while males reach sexual maturity in half that time. The conditions must be precise for a successful spawning to occur. Preparation for spawning begins in the spring with the extended photoperiod and rising water temperatures, but flooding is also necessary to trigger the event. When rivers rise and spread over the floodplain, they create oxbow lakes and sloughs, and inundate terrestrial vegetation which in turn provides protection and a nutrient rich habitat for larval fishes, and fry. Once the water temperature has reached 68 to 82 °F (20 to 28 °C), and all the other criteria are met, gars will move into the grassy, weed-laden shallows to spawn.[23][24]

Actual spawning occurs when a collection of males gather around gravid females, and begin writhing, twisting, bumping into and slithering over the tops of females, an activity which triggers the release of eggs. Males release clouds of milt to fertilize the eggs as they are released into the water column.[23] The sticky eggs then attach to submerged vegetation, and development begins. It takes only a few days for the eggs to hatch into larval fish, and another ten days or so for the larval fish to detach from the vegetation and start moving about as young fry.[24] Egg production is variable, and believed to be dependent on the size of the female. A common formula used for predicting the volume of eggs a female can produce is 4.1 eggs/gram of body weight which gives an average of about 150,000 eggs per spawn. The eggs of alligator gar are bright red and poisonous to humans if ingested.[19]

Distribution

Alligator gar caught in Moon Lake, Mississippi, March 1910

Natural range

Alligator gar inhabit a wide variety of aquatic habitats, but most are found in the Southern United States in reservoirs and lakes, in the backwaters of lowland rivers, and in the brackish waters of estuaries, bayous and bays. They have occasionally been seen in the Gulf of Mexico.[19] In Texas and Louisiana it is common to see large gars breaking the surface in reservoirs, bayous, and brackish marshes. They are found throughout the lower Mississippi River Valley and Gulf Coast states of the Southern United States and Mexico as far south as Veracruz, encompassing the following states in the United States: Texas, Oklahoma, Louisiana, Kentucky, Mississippi, Alabama, Tennessee, Arkansas, Missouri, Illinois, Florida, and Georgia.[25] Reports suggest alligator gar were once numerous throughout much of their northern range, however valid sightings today are rare, and may occur once every few years.[6] Records of historical distribution indicate alligator gar once inhabited regions as far north as central Kansas, Nebraska, Ohio, Iowa, and west-central Illinois where they are now listed as extirpated. The most northerly verified catch was in Meredosia, Illinois in 1922.[26] There are now efforts to reintroduce alligator gar between Tennessee and Illinois as part of an effort to control invasive Asian carp.[27]

Outside natural range

A few notable sightings of alligator gar have been reported outside North America. In November 2008, a broadhead gar, genus Atractosteus, measuring 5.2 to 6.4 ft (1.6 to 2.0 m) was caught in the Caspian Sea north of Esenguly, Turkmenistan by two officials of Turkmenistan Fishery Protection.[28] Its species is unconfirmed but is believed to be an alligator gar.[29]

On September 4, 2009 a 3 ft 3 in (0.99 m) alligator gar was found in Tak Wah Park in Tsuen Wan, Hong Kong. Over the next two days, at least 16 other alligator gar, the largest measuring 4.9 ft (1.5 m), were found in ponds in public parks in Hong Kong.[30] Nearby residents reported the alligator gar had been released into the ponds by aquarium hobbyists, and had lived there for several years. However, after a complaint made by a citizen who falsely identified alligator gar as crocodiles, the use of terms like "horrible man-eating fish" had begun appearing in the headlines of some major local newspapers. Officials with Leisure and Cultural Services in Tak Wah Park removed all the alligator gar from the ponds because they were concerned the large, carnivorous fish might harm children.[31] It is not unusual for the large sharp teeth and outward appearance of alligator gar to precipitate unreasonable fear in those unfamiliar with the species. Sensationalized reports have contributed to the misconception of predatory attacks by alligator gar on humans even though none of the reports have been confirmed.[32]

On January 21, 2011, an alligator gar measuring 4 ft 11 in (1.50 m) was caught in a canal in Pasir Ris, Singapore by two recreational fishermen. The fish was taken to a nearby pond where the owner confirmed it was an alligator gar rather than an arapaima as the men had initially thought.[33]

There have been anecdotal reports of alligator gar captured in various parts of India but are believed to be the result of incidental releases by aquarium hobbyists and the like. In August 2015, an alligator gar was found entangled in cloth inside a well in Dadar where it had been living for quite some time. It was rescued by animal activists and returned to the well unharmed.[34] In June 2016, a 3.5 ft Alligator Gar was caught from Subhash Sarovar Lake in Kolkata.[35] Other incidents over the years have been random, ranging anywhere from captures in coastal waters during environmental assessments[36] to captures in private ponds.

Human utilization

Early history

Native Americans in the south, and Caribbean peoples used the alligator gar's ganoid scales for arrow heads, breastplates, and as shielding to cover plows. Early settlers tanned the skins to make a strong, durable leather to cover their wooden plows, make purses, and various other items. Gar oil was also used by the people of Arkansas as a repellent for buffalo-gnats.[21]

For nearly half a century, alligator gar were considered "trash fish",[2] or a "nuisance species" by state and federal authorities who targeted them for elimination to protect game fish populations,[4] and to prevent alleged attacks on humans, a claim that remains unsubstantiated with the exception of occasional injuries sustained from captured alligator gar thrashing around on the decks of boats.[19] Fishermen participated in the slaughter of thousands of alligator gar believing they were providing a great service. In 1995, KUHT channel 8, a member PBS television station located on the campus of the University of Houston in Texas, distributed and broadcast the first video documentary ever produced on alligator gar. The documentary, "Alligator Gar:Predator or Prey?", debuted nationally in prime time during the July Sweeps, and according to the Nielsen rating report provided to KUHT, was the number one rated program of the evening.[19] The documentary focused on the physiology and life cycle of alligator gar, addressed the destruction of habitat, the unregulated culling and over harvesting of alligator gar from various lakes in Texas and Louisiana, and expressed concerns for the future of the species at a time when they were still considered a "trash fish".[19] A decade passed before any significant action was taken to protect and preserve the remaining populations of alligator gar in the United States. The Missouri Department of Conservation has since partnered with Tennessee, Arkansas, Kentucky, Illinois, Alabama, Mississippi, Texas, Oklahoma, and Louisiana in restoration and management activities.[21]

Alligator gar ganoid scale jewelry.jpg Earrings from the ganoid scales of alligator gar.jpg AlligatorGarHarvest.jpg Filleting an alligator gar.jpg AlligatorGarPrice.jpg Alligator gar fillets on the grill.jpg
Ganoid scale jewelry Ganoid scale earrings 1995 Choke Canyon Harvest On site processing Market display of gar fillets Fillets grilled, and crab boiled

Sport fish

6 ft (1.8 m) 129 lb (59 kg) alligator gar caught by Steve Zeug and Clint Robertson, Brazos River, Texas, 2004

The long time public perception of alligator gar as "trash fish", or a "nuisance species" has changed with increasing national and international attention on the species as a sport fish which some have attributed to features on popular television shows. Oklahoma, Texas, Arkansas, Mississippi, and Louisiana allow regulated sport fishing of alligator gar. Texas has one of the best remaining fisheries for alligator gar, and in concert with its efforts to maintain a viable fishery, imposed a one-per-day bag limit on them in 2009.[37] The Texas state record, and world record for the largest alligator gar caught on rod and reel is 279 lb (127 kg), taken by Bill Valverde on January 1, 1951 on the Rio Grande in Texas.[38] Alligator gar are also quite popular among bowfishers because of their large size, trophy potential, and fighting ability. The Texas state bowfishing record was set In 2001 by Marty McClellan with a 290 lb (130 kg) alligator gar from the Trinity River. The all-tackle record was a 302 lb (137 kg) alligator gar caught on a trotline in 1953 by T.C. Pierce, Jr. In 1991, fishing guide Kirk Kirkland anecdotally reported catching an alligator gar measuring 9 ft 6 in (2.90 m) on rod and line from the Trinity River.[39]

Commercialization and aquaculture

Declining populations of alligator gar throughout their historic range has resulted in the need to monitor wild populations and regulate commercial harvests. Alligator gar have a high yield of white meat fillets and a small percentage of waste relative to body weight. The meat is sold to wholesale distributors, and also sold retail by a few supermarkets with prices starting at around $3.00/lb. Fried gar balls, grilled fillets, and fillets boiled in water with crab boil seasoning are popular dishes in the south. There is also a small cottage industry that makes jewelry out of ganoid scales, and tans gar hides to produce leather for making lamp shades, purses, and a host of novelty items.[19][21]

Atractosteus gars, including alligator gar, tropical gars, and Cuban gars are considered good candidates for aquaculture particularly in developing regions where their rapid growth, disease resistance, easy adaptation to artificial feeds as juveniles, and ability to tolerate low water quality are essential. Their ability to breathe in both air and water eliminates the need for costly aeration systems and other technology commonly used in aquaculture. In the Southern United States, as well as in parts of Mexico and Cuba, broodstocks have already been established, and are being maintained in their respective regions where they already are a popular food fish.[40]

Aquaria

Alligator gar maneuvering with pectoral fins in large zoo aquarium

Despite the large size alligator gar can attain, they are kept as aquarium fish, though many fish labeled as "alligator gar" in the aquarium trade are actually smaller species. Alligator gar require a very large aquarium or pond, and ample resources in order for them to thrive in captivity. They are also a popular fish for public aquaria, and zoos. It is illegal in many areas to keep alligator gar as pets, but they will occasionally show up in fish stores. Alligator gar are highly prized and sought after for private aquaria, particularly in Japan. According to some reports, large alligator gar could fetch as much as US$40,000 in what some consider the "Japanese black market".[41] In June 2011, three men from Florida and Louisiana were indicted on charges of illegally removing wild alligator gar from the Trinity River in Texas, and attempting to ship them to Japan for private collectors. The indictments resulted from an undercover sting operation by special agents with the U.S. Fish & Wildlife Service, the Texas Parks and Wildlife Department, and the Florida Fish and Wildlife Conservation Commission.[42] The charges included violations of three separate provisions of the Lacey Act, specifically conspiracy to submit a false label for fish transported in interstate commerce; conspiracy to transport fish in interstate commerce in violation of state law or regulation; and conspiracy to transport and sell fish in interstate commerce in violation of state law or regulation.[43] Two of the conspirators entered guilty pleas to one count, and the government dropped the other two charges against them. A third conspirator went to trial on all three counts, was acquitted on one count, and found guilty on two. The district court sentenced him to serve nine months in prison followed by one year of supervised release.[44] The case was appealed, and on April 15, 2014, the appellate court affirmed the judgment of the district court.[45]

References

  1. ^ Froese, R.; Pauly, D. (2017). "Lepisosteidae". FishBase version (02/2017). Retrieved 18 May 2017. 
  2. ^ a b Brady, Tony (August 2013). "Fleur De Lis Fisheries" (PDF). US Fish & Wildlife Service. p. 2. 
  3. ^ Milbrath, Lester W. (1989). Envisioning a Sustainable Society: Learning Our Way Out. SUNY Press. p. 271. ISBN 9780791401620. 
  4. ^ a b Echevarria, Carlos (February 5, 2013). "Alligator Gar, Atractosteus spatula". Warm Springs National Fish Hatchery. US Fish & Wildlife Service. Retrieved July 7, 2014. 
  5. ^ Lochmann, S.E.; Baker, Brandon W.; Rachels, Kyle T.; Timmons, Brett A. "New Research". Aquaculture and Fisheries Center. University of Arkansas at Pine Bluff. Retrieved June 18, 2014. 
  6. ^ a b c d e Goddard, Nathaniel. "Alligator Gar". FLMNH Ichthyology Department. Retrieved April 19, 2014. 
  7. ^ "Alligator Gar (Atractosteus spatula)". Texas Parks & Wildlife Department. Retrieved March 8, 2016. 
  8. ^ "Vicksburg Man Catches 327 Lb. Alligator Gar". WAPT News. February 18, 2011. Archived from the original on February 9, 2013. 
  9. ^ Love, Chad (February 23, 2011). "World Record Alligator Gar Pulled From Mississippi Lake Tangled in Fisherman's Net". Field & Stream. Retrieved April 19, 2014. 
  10. ^ Tyus, Harold M. (2011). Ecology and Conservation of Fishes. CRC Press. p. 46. ISBN 9781439858547. 
  11. ^ "Biology of Fishes-Fish/Biol 311" (PDF). Swimbladder. University of Washington. Retrieved August 2, 2014. 
  12. ^ Perkins, Sid (September 23, 2015). "How The Enamel That Coats Your Teeth Evolved". AAAS. Retrieved January 6, 2017. 
  13. ^ "Tooth Enamel May Have Evolved From Ancient Fish Scales". ABC Science. September 24, 2015. Retrieved January 6, 2017. 
  14. ^ Sherman, Vincent R.; Yaraghi, Nicholas A.; Kisailus, David; Meyers, Marc A. (2016-12-01). "Microstructural and geometric influences in the protective scales of Atractosteus spatula". Journal of The Royal Society Interface. 13 (125): 20160595. ISSN 1742-5689. PMID 27974575. doi:10.1098/rsif.2016.0595. 
  15. ^ Schwartz, Daniel E.; Allen, Peter J. (December 2013). "Comparative biochemistry and physiology. Part A, Molecular and integrative physiology". Mississippi State University Dept. of Wildlife, Fisheries and Aquaculture. 
  16. ^ "The American Naturalist". 35. University of Chicago Press. JSTOR 2453768. 
  17. ^ Warren, Melvin L. Jr.; Burr, Brooks M. Freshwater Fishes of North America. 1. Johns Hopkins University Press. p. 250. ISBN 1421412012. 
  18. ^ Mayor, Adrienne (2005). Fossil Legends of the First Americans. Princeton University Press. p. 38. ISBN 9781400849314. 
  19. ^ a b c d e f g h "Alligator Gar (Atractosteus spatula)". 2011. Retrieved January 6, 2017. 
  20. ^ Graham, Jeffrey B. (1997). Air-Breathing Fishes: Evolution, Diversity, and Adaptation. Academic Press. pp. 1–10. ISBN 0-12-294860-2. 
  21. ^ a b c d "Missouri Alligator Gar Management and Restoration Plan" (PDF). Missouri Department of Conservation Fisheries Division. January 22, 2013. Archived from the original (PDF) on May 6, 2016. Retrieved August 1, 2016. 
  22. ^ Buckmeier, David L. (July 31, 2008). "Life History and Status of Alligator Gar (Atractosteus spatula), with Recommendations for Management" (PDF). Heart of Hills Fisheries Science Center. Texas Parks and Wildlife Department. p. 5. Retrieved July 7, 2014. 
  23. ^ a b "BBest Recommendations Report" (PDF). Sabine/Neches BBest Biological Overlay Approach. Best Biological Subcommittee, Texas Commission on Environmental Quality, U.S. November 2, 2009. p. 8. Retrieved July 7, 2014. 
  24. ^ a b Thompkins, Shannon (April 19, 2014). "Once a nuisance, alligator gar increasingly protected". Houston Chronicle. 
  25. ^ "Alligator Gar Technical Committee". Southern Division of the American Fisheries Society. Archived from the original on November 4, 2013. Retrieved May 17, 2013. 
  26. ^ Poly, William J. (2001). "Distribution of the Alligator Gar, Atractosteus spatula (Lacépède, 1803), in Illinois" (PDF). Transactions of the Illinois State Academy of Science. 94 (3): 185–190. 
  27. ^ Webber, Tammy (July 29, 2016). "Huge, once-hated fish now seen as weapon against Asian carp". Pantagraph. Associated Press. Retrieved July 31, 2016. [permanent dead link]
  28. ^ "Hazar deňziniň türkmen kenarynda amerikan sowutly çortanyň tutulmagynyň ilkinji wakasy" (in Turkmen). Türkmenistanyň Tebigaty goramak ministrligi. Retrieved May 18, 2015. 
  29. ^ Salnikov, V. B. (April 2011). "Russian Journal of Biological Invasions". Erratum to: "First Finding of Gar Atractosteus sp. (Actinopterygii, Lepisosteiformes, Lepisosteidae) in the Caspian Sea near the Coast of Turkmenistan". Springer. 2 (2): 240. doi:10.1134/S2075111711030118. 
  30. ^ "Monster Exotic Fish Found In Hong Kong Ponds". ABS-CBN News. September 5, 2009. Retrieved July 4, 2016. 
  31. ^ Nip, Amy (January 10, 2010). "Feared in public ponds, admired behind glass". South China Morning Post. 
  32. ^ Spitzer, Mark. "When Gars Attack". Southeast Missouri State University. Retrieved July 4, 2016. 
  33. ^ "Friends Catch 1.5m 'Monster' Fish From Pasir Ris Canal After Long Struggle". The Straits Times. January 21, 2011. [permanent dead link]
  34. ^ Singh, Vijay (August 6, 2015). "Exotic Alligator Gar fish rescued in Dadar". The Times of India. Bennett, Coleman & Co. Ltd. Retrieved December 6, 2015. 
  35. ^ Kolkata: Discovery of predator fish that resembles an alligator concerns experts. Hindustan Times (June 22, 2016). Retrieved on 2016-11-10.
  36. ^ Kumaraguru, A.K.; Kannan, R. and Sundaramahalingam, A. (March 2000). "Studies on Socioeconomics of Coral Reef Resource Users in the Gulf of Mannar Coast, South India" (PDF). Planning Commission Project. Centre for Marine and Coastal Studies. Retrieved December 6, 2015. CS1 maint: Uses authors parameter (link)
  37. ^ "Alligator Gar". Texas Parks and Wildlife Department. Retrieved April 21, 2014. 
  38. ^ "State Freshwater Records: Rod and Reel". Texas Parks & Wildlife. Retrieved May 17, 2013. 
  39. ^ "Big Fish Stories Can Have Happier Endings". Texas Parks & Wildlife. May 16, 2011. 
  40. ^ Alfaro, Roberto M.; Gonzales, Carlos A.; Ferrara, Allyse (2008). "Gar biology and culture: status and prospects" (PDF). Chapter 39. Aquaculture Research. pp. 748–763. Retrieved July 7, 2014. 
  41. ^ Horswell, Cindy (June 17, 2011). "Indictments accuse 3 of taking alligator gar fish out of Trinity". Houston Chronicle. 
  42. ^ Berstein, Jon (October 15, 2011). "Monster fish tale: Alligator gar sting ends in conviction". SunSentinel. 
  43. ^ "Accused alligator gar smugglers busted in trinity river operation". ABC 9 KTRE. 2011. 
  44. ^ "United States v. Loren Willis et al., Nos. 9:11-CR-00028, 1:11-CR-20676 (E.D. Tex., S.D. Fla.), AUSAs Reynaldo Morin and Jaime Raiche" (PDF). Monthly Bulletin. Regional EnvironmentalEnforcement Association. October 2012. Retrieved July 4, 2016. 
  45. ^ "Opinions" (PDF). U.S. Court of Appeals. April 15, 2014. 

Further reading

External links

source: http://en.wikipedia.org/wiki/Alligator_gar

White-tailed Deer Skull

White-tailed Deer Skull Print by Inked Animal

White-tailed Deer | Odocoileus virginianus


White-tailed Deer info via Wikipedia:

White-tailed deer
White-tailed deer.jpg
Male white-tailed deer (buck or stag)
Whitetail doe.jpg
Female white-tailed deer (doe)
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Family: Cervidae
Subfamily: Capreolinae
Genus: Odocoileus
Species: O. virginianus
Binomial name
Odocoileus virginianus
(Zimmermann, 1780)
Subspecies

38, see text

Odocoileus virginianus map.svg
White-tailed deer range map
Synonyms
  • Dama virginiana Zimmermann, 1780
  • Dama virginianus Zimmermann, 1780

The white-tailed deer (Odocoileus virginianus), also known as the whitetail, is a medium-sized deer native to the United States, Canada, Mexico, Central America, and South America as far south as Peru and Bolivia.[2] It has also been introduced to New Zealand, Cuba, Jamaica, Hispaniola, Puerto Rico, Bahamas, Lesser Antilles, and some countries in Europe, such as Finland, the Czech Republic, and Serbia.[3][4][5] In the Americas, it is the most widely distributed wild ungulate.

In North America, the species is widely distributed east of the Rocky Mountains, but elsewhere, it is mostly replaced by the black-tailed or mule deer (Odocoileus hemionus). In western North America, it is found in aspen parklands and deciduous river bottomlands within the central and northern Great Plains, and in mixed deciduous riparian corridors, river valley bottomlands, and lower foothills of the northern Rocky Mountain regions from South Dakota and Wyoming to northeastern British Columbia, including the Montana Valley and Foothill grasslands.

The conversion of land adjacent to the northern Rockies into agriculture use and partial clear-cutting of coniferous trees (resulting in widespread deciduous vegetation) has been favorable to the white-tailed deer and has pushed its distribution to as far north as Fort St. John, British Columbia. Populations of deer around the Great Lakes have also expanded their range northwards, due to conversion of land to agricultural uses favoring more deciduous vegetation, and local caribou and moose populations. The westernmost population of the species, known as the Columbian white-tailed deer, once was widespread in the mixed forests along the Willamette and Cowlitz River valleys of western Oregon and southwestern Washington, but today its numbers have been considerably reduced, and it is classified as near-threatened.

Taxonomy

Fawn waving its white tail

Some taxonomists have attempted to separate white-tailed deer into a host of subspecies, based largely in morphological differences. Genetic studies,[clarification needed] however, suggest fewer subspecies within the animal's range, as compared to the 30 to 40 subspecies that some scientists described in the last century. The Florida Key deer, O. virginianus clavium, and the Columbian white-tailed deer, O. virginianus leucurus, are both listed as endangered under the U.S. Endangered Species Act. In the United States, the Virginia white-tail, O. virginianus virginianus, is among the most widespread subspecies. The white-tailed deer species has tremendous genetic variation and is adaptable to several environments. Several local deer populations, especially in the southern states, are descended from white-tailed deer transplanted from various localities east of the Continental Divide. Some of these deer populations may have been from as far north as the Great Lakes region to as far west as Texas, yet are also quite at home in the Appalachian and Piedmont regions of the south. These deer over time have intermixed with the local indigenous deer (O. virginianus virginianus and/or O. virginianus macrourus) populations.

Male whitetail in Kansas

Central and South America have a complex number of white-tailed deer subspecies that range from Guatemala as far south as Peru. This list of subspecies of deer is more exhaustive than the list of North American subspecies, and the number of subspecies is also questionable. However, the white-tailed deer populations in these areas are difficult to study, due to overhunting in many parts and a lack of protection. Some areas no longer carry deer, so it is difficult to assess the genetic difference of these animals.

Subspecies

O. v. truei, female, Costa Rica
Three O. v. borealis, New Hampshire

Some subspecies names, ordered alphabetically:[6][7]

North America

  • O. v. acapulcensis – Acapulco white-tailed deer (southern Mexico)
  • O. v. borealis – northern (woodland) white-tailed deer (the largest and darkest white-tailed deer)
  • O. v. carminis – Carmen Mountains Jorge deer (Texas-Mexico border)
  • O. v. clavium – Key deer or Florida Keys white-tailed deer (found in the Florida Keys; an example of insular dwarfism)
  • O. v. chiriquensis – Chiriqui white-tailed deer (Panama)
  • O. v. couesi – Coues white-tailed deer, Arizona white-tailed deer, or fantail deer
  • O. v. dakotensis – Dakota white-tailed deer or Northern Plains white-tailed deer (most northerly distribution, rivals the northern white-tailed deer in size)
  • O. v. hiltonensis – Hilton Head Island white-tailed deer
  • O. v. idahoensis – white-tailed deer (western Canada, Idaho, eastern Washington)[8]
  • O. v. leucurus – Columbian white-tailed deer (Oregon and western coastal area)
  • O. v. macrourus – Kansas white-tailed deer
  • O. v. mcilhennyi – Avery Island white-tailed deer
  • O. v. mexicanus – Mexican white-tailed deer (central Mexico)
  • O. v. miquihuanensis – Miquihuan white-tailed deer (central Mexico)
  • O. v. nelsoni – Chiapas white-tailed deer (southern Mexico and Guatemala)
  • O. v. nemoralis – (Central America, round the Gulf of Mexico to Surinam in South America; further restricted to from Honduras to Panama)
  • O. v. nigribarbis – Blackbeard Island white-tailed deer
  • O. v. oaxacensis – Oaxaca white-tailed deer (southern Mexico)
  • O. v. ochrourus – (tawny) northwest white-tailed deer or northern Rocky Mountains white-tailed deer
  • O. v. osceola – Florida coastal white-tailed deer
  • O. v. rothschildi – Coiba Island white-tailed deer
  • O. v. seminolus – Florida white-tailed deer
  • O. v. sinaloae – Sinaloa white-tailed deer (mid-western Mexico)
  • O. v. taurinsulae – Bulls Island white-tailed deer (Bulls Island, South Carolina)
  • O. v. texanus – Texas white-tailed deer
  • O. v. thomasi – Mexican lowland white-tailed deer
  • O. v. toltecus – Rain Forest white-tailed deer (southern Mexico)
  • O. v. truei – Central American white-tailed deer (Costa Rica, Nicaragua and adjacent states)
  • O. v. venatorius – Hunting Island white-tailed deer (Hunting Island, South Carolina)
  • O. v. veraecrucis – northern Veracruz white-tailed deer
  • O. v. virginianus – Virginia white-tailed deer or southern white-tailed deer
  • O. v. yucatanensis – Yucatán white-tailed deer

South America

Range map of subspecies
North America
Central and South America
White-tailed deer buck seen in Missoula, Montana.

Description

Female with tail in alarm posture

The deer's coat is a reddish-brown in the spring and summer and turns to a grey-brown throughout the fall and winter. The deer can be recognized by the characteristic white underside to its tail. It raises its tail when it is alarmed to warn the predator that it has been detected.[9] A population of white-tailed deer in New York is entirely white (except for areas like their noses and toes)—not albino—in color. The former Seneca Army Depot in Romulus, New York, has the largest known concentration of white deer. Strong conservation efforts have allowed white deer to thrive within the confines of the depot. White-tailed deer's horizontally slit pupils allow for good night vision and color vision during the day.

Size and weight

Close up of female's head

The white-tailed deer is highly variable in size, generally following Bergmann's rule that the average size is larger farther away from the Equator. North American male deer (also known as a buck) usually weigh 45 kilograms (100 lb), but in rare cases, bucks in excess of 125 kilograms (275 lb) have been recorded. Mature bucks over 180 kilograms (400 lb) have been recorded in the northernmost reaches of their native range, specifically, Minnesota and Ontario. In 1926, Carl J. Lenander, Jr. took a white-tailed buck near Tofte, MN, that weighed 183 kg (403 lb) after it was field-dressed (internal organs removed) and was estimated at 232 kg (511 lb) when alive.[10] The female (doe) in North America usually weighs from 40 to 90 kg (88 to 198 lb). White-tailed deer from the tropics and the Florida Keys are markedly smaller-bodied than temperate populations, averaging 35 to 50 kg (77 to 110 lb), with an occasional adult female as small as 25 kg (55 lb).[11] White-tailed deer from the Andes are larger than other tropical deer of this species and have thick, slightly woolly looking fur. Length ranges from 95 to 220 cm (37 to 87 in), including a tail of 10 to 36.5 cm (3.9 to 14.4 in), and the shoulder height is 53 to 120 cm (21 to 47 in).[12][13] Including all races, the average summer weight of adult males is 68 kg (150 lb) and is 45.3 kg (100 lb) in adult females.[14]

Deer have dichromatic (two-color) vision with blue and yellow primaries;[15] humans normally have trichromatic vision. Thus, deer poorly distinguish the oranges and reds that stand out so well to humans.[16] This makes it very convenient to use deer-hunter orange as a safety color on caps and clothing to avoid accidental shootings during hunting seasons.

Antlers

Male white-tailed deer

Males regrow their antlers every year. About one in 10,000 females also have antlers, although this is usually associated with freemartinism.[17] Bucks without branching antlers are often termed "spikehorn", "spiked bucks", "spike bucks", or simply "spikes/spikers". The spikes can be quite long or very short. Length and branching of antlers are determined by nutrition, age, and genetics. Rack growth tends to be very important from late spring until about a month before velvet sheds. Healthy deer in some areas that are well-fed can have eight-point branching antlers as yearlings (1.5 years old).[18] The number of points, the length, or thickness of the antlers is a general indication of age, but cannot be relied upon for positive aging. A better indication of age is the length of the snout and the color of the coat, with older deer tending to have longer snouts and grayer coats. Some say spiked-antler deer should be culled from the population to produce larger branching antler genetics (antler size does not indicate overall health), and some bucks' antlers never will be wall trophies. Good antler-growth nutritional needs (calcium) and good genetics combine to produce wall trophies in some of their range.[19] Spiked bucks are different from "button bucks" or "nubbin' bucks", that are male fawns and are generally about six to nine months of age during their first winter. They have skin-covered nobs on their heads. They can have bony protrusions up to a half inch in length, but that is very rare, and they are not the same as spikes.

White-tailed bucks with antlers still in velvet, August 2011

Antlers begin to grow in late spring, covered with a highly vascularised tissue known as velvet. Bucks either have a typical or atypical antler arrangement. Typical antlers are symmetrical and the points grow straight up off the main beam. Atypical antlers are asymmetrical and the points may project at any angle from the main beam. These descriptions are not the only limitations for typical and atypical antler arrangement. The Boone and Crockett or Pope and Young scoring systems also define relative degrees of typicality and atypicality by procedures to measure what proportion of the antlers are asymmetrical. Therefore, bucks with only slight asymmetry are scored as "typical". A buck's inside spread can be from 3 to 25 in (8–64 cm). Bucks shed their antlers when all females have been bred, from late December to February.

Ecology

White-tailed deer are generalists and can adapt to a wide variety of habitats.[20] The largest deer occur in the temperate regions of Canada and United States. The northern white-tailed deer (O. v. borealis), Dakota white-tailed deer (O. v. dacotensis), and northwest white-tailed deer (O. v. ochrourus) are some of the largest animals, with large antlers. The smallest deer occur in the Florida Keys and in partially wooded lowlands in the neotropics.

Although most often thought of as forest animals depending on relatively small openings and edges, white-tailed deer can equally adapt themselves to life in more open prairie, savanna woodlands, and sage communities as in the Southwestern United States and northern Mexico. These savanna-adapted deer have relatively large antlers in proportion to their body size and large tails. Also, a noticeable difference exists in size between male and female deer of the savannas. The Texas white-tailed deer (O. v. texanus), of the prairies and oak savannas of Texas and parts of Mexico, are the largest savanna-adapted deer in the Southwest, with impressive antlers that might rival deer found in Canada and the northern United States. Populations of Arizona (O. v. couesi) and Carmen Mountains (O. v. carminis) white-tailed deer inhabit montane mixed oak and pine woodland communities.[21] The Arizona and Carmen Mountains deer are smaller, but may also have impressive antlers, considering their size. The white-tailed deer of the Llanos region of Colombia and Venezuela (O. v. apurensis and O. v. gymnotis) have antler dimensions similar to the Arizona white-tailed deer.

White-tailed deer during late winter

In western regions of the United States and Canada, the white-tailed deer range overlaps with those of the mule deer. White-tail incursions in the Trans-Pecos region of Texas have resulted in some hybrids. In the extreme north of the range, their habitat is also used by moose in some areas. White-tailed deer may occur in areas that are also exploited by elk (wapiti) such as in mixed deciduous river valley bottomlands and formerly in the mixed deciduous forest of eastern United States. In places such as Glacier National Park in Montana and several national parks in the Columbian Mountains (Mount Revelstoke National Park) and Canadian Rocky Mountains, as well as in the Yukon Territory ( Yoho National Park and Kootenay National Park), white-tailed deer are shy and more reclusive than the coexisting mule deer, elk, and moose.

Central American white-tailed deer prefer tropical and subtropical dry broadleaf forests, seasonal mixed deciduous forests, savanna, and adjacent wetland habitats over dense tropical and subtropical moist broadleaf forests. South American subspecies of white-tailed deer live in two types of environments. The first type, similar to the Central American deer, consists of savannas, dry deciduous forests, and riparian corridors that cover much of Venezuela and eastern Colombia.[22] The other type is the higher elevation mountain grassland/mixed forest ecozones in the Andes Mountains, from Venezuela to Peru. The Andean white-tailed deer seem to retain gray coats due to the colder weather at high altitudes, whereas the lowland savanna forms retain the reddish brown coats. South American white-tailed deer, like those in Central America, also generally avoid dense moist broadleaf forests.

Since the second half of the 19th century, white-tailed deer have been introduced to Europe.[23] A population in the Brdy area remains stable today.[24] In 1935, white-tailed deer were introduced to Finland. The introduction was successful, and the deer have recently begun spreading through northern Scandinavia and southern Karelia, competing with, and sometimes displacing, native species. The current population of some 30,000 deer originated from four animals provided by Finnish Americans from Minnesota.

Diet

White-tailed deer eat large amounts of food, commonly eating legumes and foraging on other plants, including shoots, leaves, cacti (in deserts), prairie forbs,[25] and grasses. They also eat acorns, fruit, and corn. Their special stomachs allow them to eat some things humans cannot, such as mushrooms and poison ivy. Their diets vary by season according to availability of food sources. They also eat hay, grass, white clover, and other foods they can find in a farm yard. Though almost entirely herbivorous, white-tailed deer have been known to opportunistically feed on nesting songbirds, field mice, and birds trapped in mist nets, if the need arises.[26]

The white-tailed deer is a ruminant, which means it has a four-chambered stomach. Each chamber has a different and specific function that allows the deer to eat a variety of different foods, digesting it at a later time in a safe area of cover. The stomach hosts a complex set of microbes that change as the deer's diet changes through the seasons. If the microbes necessary for digestion of a particular food (e.g., hay) are absent, it will not be digested.[27]

Predators

Several natural predators of white-tailed deer occur. Wolves, cougars, American alligators, jaguars (in the tropics), and humans are the most effective natural predators of white-tailed deer. These predators frequently pick out easily caught young or infirm deer (which is believed to improve the genetic stock of a population), but can and do take healthy adults of any size. Bobcats, Canada lynx, bears, wolverines, and packs of coyotes usually prey mainly on fawns. Bears may sometimes attack adult deer, while lynxes, coyotes, and wolverines are most likely to take adult deer when the ungulates are weakened by harsh winter weather.[12] Many scavengers rely on deer as carrion, including New World vultures, raptors, foxes, and corvids. Few wild predators can afford to be picky and any will readily consume deer as carrion. Records exist of American crows attempting to prey on white-tailed deer fawns by pecking around their face and eyes, though no accounts of success are given.[28] Occasionally, both golden and bald eagles may capture deer fawns with their talons.[29] In one case, a golden eagle was filmed in Illinois unsuccessfully trying to prey on a large mature white-tailed deer.[30]

White-tailed deer typically respond to the presence of potential predators by breathing very heavily (also called blowing) and fleeing. When they blow, the sound alerts other deer in the area. As they run, the flash of their white tails warns other deer. This especially serves to warn fawns when their mother is alarmed.[31] Most natural predators of white-tailed deer hunt by ambush, although canids may engage in an extended chase, hoping to exhaust the prey. Felids typically try to suffocate the deer by biting the throat. Cougars and jaguars will initially knock the deer off balance with their powerful forelegs, whereas the smaller bobcats and lynxes will jump astride the deer to deliver a killing bite. In the case of canids and wolverines, the predators bite at the limbs and flanks, hobbling the deer, until they can reach vital organs and kill it through loss of blood. Bears, which usually target fawns, often simply knock down the prey and then start eating it while it is still alive.[32][33] Alligators snatch deer as they try to drink from or cross bodies of water, grabbing them with their powerful jaws and dragging them into the water to drown.[34]

Most primary natural predators of white-tailed deer have been basically extirpated in eastern North America, with a very small number of reintroduced red wolves, which are nearly extinct, around North Carolina and a small remnant population of Florida panthers, a subspecies of the cougar. Gray wolves, the leading cause of deer mortality where they overlap, co-occur with whitetails in northern Minnesota, Wisconsin, Michigan, and parts of Canada.[31] This almost certainly plays a factor in the overpopulation issues with this species.[31] Coyotes, widespread and with a rapidly expanding population, are often the only major nonhuman predator of the species, besides an occasional domestic dog.[31] In some areas, American black bears are also significant predators.[32][33] In northcentral Pennsylvania, black bears were found to be nearly as common predators of fawns as coyotes.[35] Bobcats, still fairly widespread, usually only exploit deer as prey when smaller prey is scarce.[36] Discussions have occurred regarding the possible reintroduction of gray wolves and cougars to sections of the eastern United States, largely because of the apparent controlling effect they have through deer predation on local ecosystems, as has been illustrated in the reintroduction of wolves to Yellowstone National Park and their controlling effect on previously overpopulated elk.[37] However, due to the heavy urban development in much of the East and fear for livestock and human lives, such ideas have ultimately been rejected by local communities and/or by government services and have not been carried through.[38][39][40]

In areas where they are heavily hunted by humans, deer run almost immediately from people and are quite wary even where not heavily hunted. In most areas where hunting may occur deer seem to develop an acute sense of time and a fondness for metro parks and golf courses. This rather odd occurrence is best noted in Michigan, where in the lower peninsula around late August early September they begin to move out of less developed areas in favor of living near human settlements.

The deer of Virginia can run faster than their predators and have been recorded at speeds of 75 km (47 mi) per hour;[41] this ranks them amongst the fastest of all cervids, alongside the Eurasian roe deer. They can also jump 2.7 m (8.9 ft) high and up to 10 m (33 ft) in length. When shot at, the white-tailed deer will run at high speeds with its tail down. If frightened, the deer will hop in a zig-zag with its tail straight up. If the deer feels extremely threatened, however, it may charge the person or predator causing the threat, using its antlers or, if none are present, its head to fight off the threat.

Forest alteration

In certain parts of the eastern United States, high deer densities have caused large reductions in plant biomass, including the density and heights of certain forest wildflowers, tree seedlings, and shrubs. Although they can be seen as a nuisance species, white tail deer also play an important role in biodiversity.[42][43] At the same time, increases in browse-tolerant grasses and sedges and unpalatable ferns have often accompanied intensive deer herbivory.[44] Changes to the structure of forest understories have, in turn, altered the composition and abundance of forest bird communities in some areas.[45] Deer activity has also been shown to increase herbaceous plant diversity, particularly in disturbed areas, by reducing competitively dominant plants;[46] and to increase the growth rates of important canopy trees, perhaps by increased nutrient inputs into the soil.[47] In northeastern hardwood forests, high-density deer populations affect plant succession, particularly following clear-cuts and patch cuts. In succession without deer, annual herbs and woody plants are followed by commercially valuable, shade-tolerant oak and maple. The shade-tolerant trees prevent the invasion of less commercial cherry and American beech, which are stronger nutrient competitors, but not as shade tolerant. Although deer eat shade-tolerant plants and acorns, this is not the only way deer can shift the balance in favor of nutrient competitors. Deer consuming earlier-succession plants allows in enough light for nutrient competitors to invade. Since slow-growing oaks need several decades to develop root systems sufficient to compete with faster-growing species, removal of the canopy prior to that point amplifies the effect of deer on succession. High-density deer populations possibly could browse eastern hemlock seedlings out of existence in northern hardwood forests;[48] however, this scenario seems unlikely, given that deer browsing is not considered the critical factor preventing hemlock re-establishment at large scales.[49]

Ecologists have also expressed concern over the facilitative effect high deer populations have on invasions of exotic plant species. In a study of eastern hemlock forests, browsing by white-tailed deer caused populations of three exotic plants to rise faster than they do in the areas which are absent of deer. Seedlings of the three invading species rose exponentially with deer density, while the most common native species fell exponentially with deer density, because deer were preferentially eating the native species. The effects of deer on the invasive and native plants were magnified in cases of canopy disturbance.[50]

Methods for controlling deer populations

Several methods have been developed in attempts to curb the population of white-tailed deer and these can be separated into lethal and non-lethal strategies. Most common in the U.S is the use of extended hunting as population control.[51] In Maryland, as well as many other states, the Department of Natural Resources sets regulations on bag limits and hunting in the area depending on the deer population levels assessed.[52] Hunting seasons may fluctuate in duration, or restrictions may be set to affect how many deer or what type of deer can be hunted in certain regions. For the 2015-2016 white-tailed deer hunting season, some areas only allow for the hunting of antler-less white-tailed deer. These would include young bucks and females encouraging the culling of does who would otherwise contribute to increasing populations via offspring production.[51]

More refined than public hunting is a method referred to as Sharpshooting by the Deer Task Force in the city of Bloomington, Indiana. Sharpshooting can be an option when the area inhabited by the deer is unfit for public hunting. This strategy may work in areas close to human populations since it is done by professional marksmen and requires a submitted plan of action to the city with details on the time and location of the event as well as number of deer to be culled.[53]

Another controversial method involves trapping the deer in a net or other trap and then administering a chemical euthanizing agent or extermination via firearm. A main issue in questioning the humaneness of this method is the stress that the deer endure while trapped and awaiting extermination.[54]

Non-lethal methods include contraceptive injections, sterilization, and translocation of deer.[55] While lethal methods have municipal support as being the most effective in the short-term, there are opponents to this view who suggest that there are no significant impacts of deer extermination on the populations.[56] Opponents of contraceptive methods point out that fertility control proves ineffective over time as populations in open field systems move about. There are concerns that the contraceptives have not been adequately researched for the effect they could have on humans who consume the treated venison. Fertility control also does nothing to affect the current population and the effects their grazing may be having on the forest plant make-up.[57]

Translocation has been considered overly costly for the little benefit it provides. Deer experience high stress and are at high risk of dying in the process putting into question its humaneness.[58] Another concern in using this method is the possible spread of Chronic Wasting Disease found in the deer family and the lack of research on its effect on human populations.

Bloomington, Indiana has also seen increases in white-tailed deer populations. They play a detrimental role in the preservation of native plant species at the Griffy Lake Nature Reserve as was researched and confirmed via an enclosure study done by researchers at Indiana University.[59] Enclosures can also be used as a method for minimizing the effect of deer-grazing in small areas since plants are allowed to grow without the threat of being grazed upon before reaching stable populations in the forest understory.

Behavior

These bucks were pursuing a pair of does across the Loxahatchee River in Florida—the does lost them by entering a mangrove thicket too dense for the bucks' antlers.

Males compete for the opportunity of breeding females. Sparring among males determines a dominance hierarchy.[60] Bucks attempt to copulate with as many females as possible, losing physical condition, since they rarely eat or rest during the rut. The general geographical trend is for the rut to be shorter in duration at increased latitude. Many factors determine how intense the "rutting season" will be; air temperature is a major one. Any time the temperature rises above 40 °F (4 °C), the males do much less traveling looking for females, else they will be subject to overheating or dehydrating. Another factor for the strength in rutting activity is competition. If numerous males are in a particular area, then they compete more for the females. If fewer males or more females are present, then the selection process will not need to be as competitive.

Reproduction

Fawn lying on grass

Females enter estrus, colloquially called the rut, in the autumn, normally in late October or early November, triggered mainly by the declining photoperiod. Sexual maturation of females depends on population density, as well as availability of food.[61] Young females often flee from an area heavily populated with males. Some does may be as young as six months when they reach sexual maturity, but the average age of maturity is 18 months.[62] Copulation consists of an ejaculatory thrust[63] which takes place during a brief copulatory jump.[64]

Females give birth to one to three spotted young, known as fawns, in mid- to late spring, generally in May or June. Fawns lose their spots during the first summer and weigh from 44 to 77 lb (20 to 35 kg) by the first winter. Male fawns tend to be slightly larger and heavier than females. For the first four weeks, fawns are hidden in vegetation by their mothers, who nurse them four to five times a day. This strategy keeps scent levels low to avoid predators. After about a month, the fawns [65] are then able to follow their mothers on foraging trips. They are usually weaned after 8–10 weeks, but cases have been seen where mothers have continued to allow nursing long after the fawns have lost their spots (for several months, or until the end of fall) as seen by rehabilitators and other studies. Males leave their mothers after a year and females leave after two.

Bucks are generally sexually mature at 1.5 years old and begin to breed even in populations stacked with older bucks.

Communication

Two white-tailed deer nuzzling in Cayuga Heights, New York

White-tailed deer have many forms of communication involving sounds, scent, body language, and marking. In addition to the aforementioned blowing in the presence of danger, all white-tailed deer are capable of producing audible noises unique to each animal. Fawns release a high-pitched squeal, known as a bleat, to call out to their mothers.[66] This bleat deepens as the fawn grows until it becomes the grunt of the mature deer, a guttural sound that attracts the attention of any other deer in the area. A doe makes maternal grunts when searching for her bedded fawns.[66] Bucks also grunt, at a pitch lower than that of the doe; this grunt deepens as the buck matures. In addition to grunting, both does and bucks also snort, a sound that often signals an imminent threat. Mature bucks also produce a grunt-snort-wheeze pattern, unique to each animal, that asserts its dominance, aggression, and hostility.[66] Another way white-tailed deer communicate is through the use of their white tail. When spooked, it will raise its tail to warn the other deer in the immediate area.

Marking

White-tailed deer possess many glands that allow them to produce scents, some of which are so potent they can be detected by the human nose. Four major glands are the preorbital, forehead, tarsal, and metatarsal glands. Secretions from the preorbital glands (in front of the eye) were thought to be rubbed on tree branches, but research suggests this is not so. Scent from the forehead or sudoriferous glands (found on the head, between the antlers and eyes) is used to deposit scent on branches that overhang "scrapes" (areas scraped by the deer's front hooves prior to rub-urination). The tarsal glands are found on the upper inside of the hock (middle joint) on each hind leg. Scent is deposited from these glands when deer walk through and rub against vegetation. These scrapes are used by bucks as a sort of "sign-post" by which bucks know which other bucks are in the area, and to let does know a buck is regularly passing through the area—for breeding purposes. The scent from the metatarsal glands, found on the outside of each hind leg, between the ankle and hooves, may be used as an alarm scent. The scent from the interdigital glands, which are located between the hooves of each foot, emit a yellow waxy substance with an offensive odor. Deer can be seen stomping their hooves if they sense danger through sight, sound, or smell; this action leaves an excessive amount of odor for the purpose of warning other deer of possible danger.[citation needed]

Throughout the year, deer rub-urinate, a process during which a deer squats while urinating so urine will run down the insides of the deer's legs, over the tarsal glands, and onto the hair covering these glands. Bucks rub-urinate more frequently during the breeding season.[67] Secretions from the tarsal gland mix with the urine and bacteria to produce a strong-smelling odor. During the breeding season, does release hormones and pheromones that tell bucks a doe is in heat and able to breed. Bucks also rub trees and shrubs with their antlers and heads during the breeding season, possibly transferring scent from the forehead glands to the tree, leaving a scent other deer can detect.[68]

Sign-post marking (scrapes and rubs) is a very obvious way white-tailed deer communicate.[68] Although bucks do most of the marking, does visit these locations often. To make a rub, a buck uses his antlers to strip the bark off small-diameter trees, helping to mark his territory and polish his antlers. To mark areas they regularly pass through, bucks make scrapes. Often occurring in patterns known as scrape lines, scrapes are areas where a buck has used his front hooves to expose bare earth. They often rub-urinate into these scrapes, which are often found under twigs that have been marked with scent from the forehead glands.[citation needed]

Human interactions

Rescued fawn being kept as a pet in a farm near Cumaral, Colombia
Three White-tailed deer spotted in Buena Vista, Virginia

By the early 20th century, commercial exploitation and unregulated hunting had severely depressed deer populations in much of their range.[69] For example, by about 1930, the U.S. population was thought to number about 300,000.[70] After an outcry by hunters and other conservation ecologists, commercial exploitation of deer became illegal and conservation programs along with regulated hunting were introduced. In 2005, estimates put the deer population in the United States at around 30 million.[71] Conservation practices have proved so successful, in parts of their range, the white-tailed deer populations currently far exceed their cultural carrying capacity and the animal may be considered a nuisance.[72][73] A reduction in natural predators (which normally cull young, sick, or infirm specimens) has undoubtedly contributed to locally abundant populations.

Car that suffered major damage after striking a white-tailed deer in Wisconsin

At high population densities, farmers can suffer economic damage by deer feeding on cash crops, especially in corn and orchards. It has become nearly impossible to grow some crops in some areas unless very burdensome deer-deterring measures are taken. Deer are excellent fence-jumpers, and their fear of motion and sounds meant to scare them away is soon dulled. Timber harvesting and forest clearance have historically resulted in increased deer population densities,[74][75] which in turn have slowed the rate of reforestation following logging in some areas. High densities of deer can have severe impacts on native plants and animals in parks and natural areas; however, deer browsing can also promote plant and animal diversity in some areas.[76][77] Deer can also cause substantial damage to landscape plants in suburban areas, leading to limited hunting or trapping to relocate or sterilize them. In parts of the Eastern US with high deer populations and fragmented woodlands, deer often wander into suburban and urban habitats that are less than ideal for the species.

Deer–vehicle collisions

Motor vehicle collisions with deer are a serious problem in many parts of the animal's range, especially at night and during rutting season, causing injuries and fatalities among both deer and humans. Vehicular damage can be substantial in some cases.[78] In the United States, such collisions increased from 200,000 in 1980 to 500,000 in 1991.[79] By 2009, the insurance industry estimated 2.4 million deer–vehicle collisions had occurred over the past two years, estimating damage cost to be over 7 billion dollars and 300 human deaths. Despite the alarming high rate of these accidents, the effect on deer density is still quite low. Vehicle collisions of deer were monitored for two years in Virginia, and the collective annual mortality did not surpass 20% of the estimated deer population.[80]

Many techniques have been investigated to prevent road-side mortality. Fences or road under- or over- passes have been shown to decrease deer-vehicle collisions, but are expensive and difficult to implement on a large scale.[81][82] Roadside habitat modifications could also successfully decrease the number of collisions along roadways.[82] An essential procedure in understanding factors resulting in accidents is to quantify risks, which involves the driver's behavior in terms of safe speed and ability to observe the deer. They suggest reducing speed limits during the winter months when deer density is exceptionally high would likely reduce deer-vehicle collisions, but this may be an impractical solution.[81]

Diseases

Another issue that exists with high deer density is the spreading of infectious diseases. Increased deer populations lead to increased transmission of tick-borne diseases, which pose a threat to human health, to livestock, and to other deer. Deer are the primary host and vector for the adult black-legged tick, which transmits the Lyme disease bacterium to humans.[83] Lyme disease is the most common vector-borne disease in the country and is found in twelve states in Eastern America. In 2009, it affected more than 38,000 people. Furthermore, the incidence of Lyme disease seems to reflect deer density in the eastern United States, which suggests a strong correlation. White-tailed deer also serve as intermediate hosts for many diseases that infect humans through ticks, such as Rocky Mountain spotted fever.[79][80]

Cultural significance

Odocoileus virginianus skull, part of an exhibition on the cultural artifacts of the Cora people of Western Mexico.

In the U.S., the species is the state animal of Arkansas, Illinois, Michigan, Mississippi, Nebraska, New Hampshire, Ohio, Pennsylvania, and South Carolina, the wildlife symbol of Wisconsin, and game animal of Oklahoma. The profile of a white-tailed deer buck caps the coat of arms of Vermont and can be seen in the flag of Vermont and in stained glass at the Vermont State House. It is the national animal of Honduras and Costa Rica and the provincial animal of Canadian Saskatchewan and Finnish Pirkanmaa. Texas is home to the most white-tailed deer of any U.S. state or Canadian province, with an estimated population of over four million. Notably high populations of white-tailed deer occur in the Edwards Plateau of Central Texas. Michigan, Minnesota, Iowa, Mississippi, Missouri, New Jersey, Illinois, Wisconsin, Maryland, New York, North Dakota, Pennsylvania, and Indiana also boast high deer densities. In 1884, one of the first hunts of white-tailed deer in Europe was conducted in Opočno and Dobříš (Brdy Mountains area), in what is now the Czech Republic.

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  44. ^ Rooney, T.P. (2009). "High white-tailed deer densities benefit graminoids and contribute to biotic homogenization of forest ground-layer vegetation". Plant Ecology. 202: 103–111. doi:10.1007/s11258-008-9489-8. 
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  46. ^ Royo, Alejandro A.; Collins, Rachel; Adams, Mary Beth; Kirschbaum, Chad; Carson, Walter P. (2010). "Pervasive interactions between ungulate browsers and disturbance regimes promote temperate forest herbaceous diversity". Ecology. 91: 93–105. doi:10.1890/08-1680.1. 
  47. ^ Lucas, Richard W.; Salguero-Gómez, Roberto; Cobb, David B.; Waring, Bonnie G.; Anderson, Frank; McShea, William J.; Casper, Brenda B. (2013). "White-tailed deer (Odocoileus virginianus) positively affect the growth of mature northern red oak (Quercus rubra) trees". Ecosphere. 4: art84. doi:10.1890/ES13-00036.1. 
  48. ^ McShea, W.J. (1997). The Science of Overabundance: Deer Ecology and Population Management. Washington, DC: Smithsonian Institution Press. pp. 201–223, 249–279. ISBN 1-58834-062-7. 
  49. ^ Mladenoff, D.J.; Stearns, F. (1993). "Easter hemlock regeneration and deer browsing in the northern great lakes region: a re-examination and model simulation". Conservation Biology. 7: 889–900. doi:10.1046/j.1523-1739.1993.740889.x. 
  50. ^ Eschtruth, E.C.; J.J. Battles (2008). "Acceleration of exotic plant invasion in a forested ecosystem by a generalist herbivore". Conservation Biology. 23: 388–399. doi:10.1111/j.1523-1739.2008.01122.x. 
  51. ^ a b Kammin, Laura. "Population Control". Living with White Tailed Deer in Illinois. University of Illinois Extension. Retrieved May 27, 2016. 
  52. ^ "2015-2016 White Tailed Deer Seasons and Bag Limits". Maryland Guide to Hunting & Trapping. Maryland Department of Natural Resources. Retrieved May 27, 2016. 
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  56. ^ The Humane Society of the United States. "Wildlife Fertility Control". Controlling Deer Populations Humanely. Retrieved May 27, 2016. 
  57. ^ Kammin, Laura. "Other Control Methods". Living with White Tailed Deer in Illinois. Retrieved May 27, 2016. 
  58. ^ State of Connecticut. "White-Tailed Deer". Department of Energy and Environmental Protection. Retrieved May 27, 2016. 
  59. ^ The City of Bloomington. "Deer at the Griffy Lake Nature Preserve". The City of Bloomington. Retrieved May 27, 2016. 
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  80. ^ a b McShea, WJ. "Ecology and management of white-tailed deer in a changing world". Annals of the New York Academy of Sciences. 1249: 45–56. PMID 22268688. doi:10.1111/j.1749-6632.2011.06376.x. Retrieved April 22, 2015. 
  81. ^ a b "Targeting mitigation efforts: The role of speed limit and road edge clearance for deer–vehicle collisions". The Journal of Wildlife Management. 78: 679–688. doi:10.1002/jwmg.712. 
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  83. ^ Tackling Ticks That Spread Lyme Disease, Agricultural Research magazine, March 1998

Further reading

External links

source: http://en.wikipedia.org/wiki/White-tailed_deer

Blacktip Shark 1

Blacktip Shark by Inked Animal

Blacktip Shark | Carcharhinus limbatus

 


Blacktip Shark info via Wikipedia:

Not to be confused with the blacktip reef shark, Carcharhinus melanopterus.
Blacktip shark
Carcharhinus limbatus (2).jpg
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Order: Carcharhiniformes
Family: Carcharhinidae
Genus: Carcharhinus
Species: C. limbatus
Binomial name
Carcharhinus limbatus
(J. P. Müller & Henle, 1839)
Carcharhinus limbatus distmap.png
Range of the blacktip shark
Synonyms

Carcharias abbreviatus Klunzinger, 1871
Carcharias aethalorus Jordan & Gilbert, 1882
Carcharias ehrenbergi Klunzinger, 1871
Carcharias maculipinna Günther, 1868
Carcharias microps Lowe, 1841
Carcharias muelleri Steindachner, 1867
Carcharias phorcys Jordan & Evermann, 1903
Carcharias pleurotaenia Bleeker, 1852
Carcharhinus natator Meek & Hildebrand, 1923

The blacktip shark (Carcharhinus limbatus) is a species of requiem shark, and part of the family Carcharhinidae. It is common to coastal tropical and subtropical waters around the world, including brackish habitats. Genetic analyses have revealed substantial variation within this species, with populations from the western Atlantic Ocean isolated and distinct from those in the rest of its range. The blacktip shark has a stout, fusiform body with a pointed snout, long gill slits, and no ridge between the dorsal fins. Most individuals have black tips or edges on the pectoral, dorsal, pelvic, and caudal fins. It usually attains a length of 1.5 m (4.9 ft).

Swift, energetic piscivores, blacktip sharks are known to make spinning leaps out of the water while attacking schools of small fish. Their demeanor has been described as "timid" compared to other large requiem sharks. Both juveniles and adults form groups of varying size. Like other members of its family, the blacktip shark is viviparous; females bear one to 10 pups every other year. Young blacktip sharks spend the first months of their lives in shallow nurseries, and grown females return to the nurseries where they were born to give birth themselves. In the absence of males, females are also capable of asexual reproduction.

Normally wary of humans, blacktip sharks can become aggressive in the presence of food and have been responsible for a number of attacks on people. This species is of importance to both commercial and recreational fisheries across many parts of its range, with its meat, skin, fins, and liver oil used. It has been assessed as Near Threatened by the IUCN, on the basis of its low reproductive rate and high value to fishers.

Taxonomy

The blacktip shark was first described by French zoologist Achille Valenciennes as Carcharias (Prionodon) limbatus in Johannes Müller and Friedrich Henle's 1839 Systematische Beschreibung der Plagiostomen. The type specimens were two individuals caught off Martinique, both of which have since been lost. Later authors moved this species to the genus Carcharhinus.[1][2] The specific epithet limbatus is Latin for "bordered", referring to the black edges of this shark's fins.[3] Other common names used for the blacktip shark include blackfin shark, blacktip whaler, common or small blacktip shark, grey shark, and spotfin ground shark.[4]

Phylogeny and evolution

The closest relatives of the blacktip shark were originally thought to be the graceful shark (C. amblyrhynchoides) and the spinner shark (C. brevipinna), due to similarities in morphology and behavior. However, this interpretation has not been borne out by studies of mitochondrial and ribosomal DNA, which instead suggest affinity with the blacknose shark (C. acronotus). More work is required to fully resolve the relationship between the blacktip shark and other Carcharhinus species.[5]

Analysis of mitochondrial DNA has also revealed two distinct lineages within this species, one occupying the western Atlantic and the other occupying the eastern Atlantic, Indian, and Pacific Oceans. This suggests that Indo-Pacific blacktip sharks are descended from those in the eastern Atlantic, while the western Atlantic sharks became isolated by the widening Atlantic Ocean on one side and the formation of the Isthmus of Panama on the other. Blacktip sharks from these two regions differ in morphology, coloration, and life history characteristics, and the eastern Atlantic lineage may merit species status.[6] Fossil teeth belonging to this species have been found in Early Miocene (23–16 Ma) deposits in Delaware and Florida.[7][8]

Description

The blacktip shark has a robust, streamlined body with a long, pointed snout and relatively small eyes. The five pairs of gill slits are longer than those of similar requiem shark species.[1] The jaws contain 15 tooth rows on either side, with two symphysial teeth (at the jaw midline) in the upper jaw and one symphysial tooth in the lower jaw. The teeth are broad-based with a high, narrow cusp and serrated edges.[2] The first dorsal fin is tall and falcate (sickle-shaped) with a short free rear tip; no ridge runs between the first and second dorsal fins. The large pectoral fins are falcate and pointed.[1]

The coloration is gray to brown above and white below, with a conspicuous white stripe running along the sides. The pectoral fins, second dorsal fin, and the lower lobe of the caudal fin usually have black tips. The pelvic fins and rarely the anal fin may also be black-tipped. The first dorsal fin and the upper lobe of the caudal fin typically have black edges.[1] Some larger individuals have unmarked or nearly unmarked fins.[3] Blacktip sharks can temporarily lose almost all their colors during blooms, or "whitings", of coccolithophores.[9] This species attains a maximum known length of 2.8 m (9.2 ft), though 1.5 m (4.9 ft) is more typical, and a maximum known weight of 123 kg (271 lb).[4]

Distribution and habitat

A blacktip shark swimming in murky water off Oahu, Hawaii

The blacktip shark has a worldwide distribution in tropical and subtropical waters. In the Atlantic, it is found from Massachusetts to Brazil, including the Gulf of Mexico and the Caribbean Sea, and from the Mediterranean Sea, Madeira, and the Canary Islands to the Democratic Republic of the Congo. It occurs all around the periphery of the Indian Ocean, from South Africa and Madagascar to the Arabian Peninsula and the Indian subcontinent, to Southeast Asia. In the western Pacific, it is found from the Ryukyu Islands of Japan[10] to northern Australia, including southern China, the Philippines and Indonesia. In the eastern Pacific, it occurs from Baja California to Peru. It has also been reported at a number of Pacific islands, including New Caledonia, Tahiti, the Marquesas, Hawaii, Revillagigedo, and the Galápagos.[1]

Most blacktip sharks are found in water less than 30 m (98 ft) deep over continental and insular shelves, though they may dive to 64 m (210 ft).[4] Favored habitats are muddy bays, island lagoons, and the drop-offs near coral reefs; they are also tolerant of low salinity and enter estuaries and mangrove swamps. Although an individual may be found some distance offshore, blacktip sharks do not inhabit oceanic waters.[1] Seasonal migration has been documented for the population off the east coast of the United States, moving north to North Carolina in the summer and south to Florida in the winter.[11]

Biology and ecology

The blacktip shark is an extremely fast, energetic predator that is usually found in groups of varying size.[3] Segregation by sex and age does not occur; adult males and nonpregnant females are found apart from pregnant females, and both are separated from juveniles.[1] In Terra Ceia Bay, Florida, a nursery area for this species, juvenile blacktips form aggregations during the day and disperse at night. They aggregate most strongly in the early summer when the sharks are youngest, suggesting that they are seeking refuge from predators (mostly larger sharks) in numbers.[12] Predator avoidance may also be the reason why juvenile blacktips do not congregate in the areas of highest prey density in the bay.[13] Adults have no known predators.[2] Known parasites of the blacktip shark include the copepods Pandarus sinuatus and P. smithii, and the monogeneans Dermophthirius penneri and Dionchus spp., which attach the shark's skin.[2][14][15] This species is also parasitized by nematodes in the family Philometridae, which infest the ovaries.[16]

Behaviour

Blacktip sharks are social and usually found in groups.

Like the spinner shark, the blacktip shark is known to leap out of the water and spin three or four times about its axis before landing. Some of these jumps are the end product of feeding runs, in which the shark corkscrews vertically through schools of small fish and its momentum launches it into the air.[3] Observations in the Bahamas suggest that blacktip sharks may also jump out of the water to dislodge attached sharksuckers (Echeneis naucrates), which irritate the shark's skin and compromise its hydrodynamic shape.[17] The speed attained by the shark during these jumps has been estimated to average 6.3 m/s (21 ft/s).[18]

Blacktip sharks have a timid disposition and consistently lose out to Galapagos sharks (C. galapagensis) and silvertip sharks (C. albimarginatus) of equal size when competing for food.[1] If threatened or challenged, they may perform an agonistic display: the shark swims towards the threat and then turns away, while rolling from side to side, lowering its pectoral fins, tilting its head and tail upwards, and making sideways biting motions. The entire sequence lasts around 25 seconds. This behavior is similar to the actions of a shark attempting to move a sharksucker; one of these behaviors possibly is derived from the other.[19]

Feeding

Fish make up some 90% of the blacktip shark's diet.[20] A wide variety of fish have been recorded as prey for this species: sardines, herring, anchovies, ladyfish, sea catfish, cornetfish, flatfish, threadfins, mullet, mackerel, jacks, groupers, snook, porgies, mojarras, emperors, grunts, butterfish, tilapia, triggerfish, boxfish, and porcupinefish. They also feed on rays and skates, as well as smaller sharks such as smoothhounds and sharpnose sharks. Crustaceans and cephalopods are occasionally taken.[1] In the Gulf of Mexico, the most important prey of the blacktip shark is the Gulf menhaden (Brevoortia patronus), followed by the Atlantic croaker (Micropogonias undulatus).[20] Off South Africa, jacks and herring are the most important prey.[21] Hunting peaks at dawn and dusk.[20] The excitability and sociability of blacktip sharks makes them prone to feeding frenzies when large quantities of food are suddenly available, such as when fishing vessels dump their refuse overboard.[1]

Life history

As with other requiem sharks, the blacktip shark exhibits vivipary. Females typically give birth to four to seven (range one to 10) pups every other year, making use of shallow coastal nurseries that offer plentiful food and fewer predators.[1] Known nurseries include Pine Island Sound, Terra Ceia Bay, and Yankeetown along the Gulf Coast of Florida, Bulls Bay on the coast of South Carolina, and Pontal do Paraná on the coast of Brazil.[22][23] Although adult blacktip sharks are highly mobile and disperse over long distances, they are philopatric and return to their original nursery areas to give birth. This results in a series of genetically distinct breeding stocks that overlap in geographic range.[22][24]

Mating occurs from spring to early summer, and the young are born around the same time the following year after a gestation period of 10–12 months.[1] Females have one functional ovary and two functional uteri; each uterus is separated into compartments with a single embryo inside each.[25] The embryos are initially sustained by a yolk sac; in the 10th or 11th week of gestation, when the embryo measures 18–19 cm long (7.1–7.5 in), the supply of yolk is exhausted and the yolk sac develops into a placental connection that sustains the embryo until birth.[11] The length at birth is 55–60 cm (22–24 in) off the eastern United States and 61–65 cm (24–26 in) off North Africa.[11][25] The mortality rate in the first 15 months of life is 61–91%, with major threats being predation and starvation.[26] The young remain in the nurseries until their first fall, when they migrate to their wintering grounds.[11]

The growth rate of this species slows with age: 25–30 cm (9.8–11.8 in) in the first six months, then 20 cm (7.9 in) a year until the second year, then 10 cm (3.9 in) a year until maturation, then 5 cm (2.0 in) a year for adults.[27][28] The size at maturity varies geographically: males and females mature at 1.4–1.5 m (4.6–4.9 ft) and 1.6 m (5.2 ft), respectively, in the northeastern Atlantic,[11] 1.3–1.4 m (4.3–4.6 ft) and 1.5–1.6 m (4.9–5.2 ft), respectively, in the Gulf of Mexico,[27][29] 1.5 and 1.6 m (4.9 and 5.2 ft) respectively off South Africa,[30] and 1.7 and 1.8 m (5.6 and 5.9 ft), respectively, off North Africa.[25] The age at maturation is 4–5 years for males and 7–8 years for females.[27][29] The lifespan is at least 12 years.[1]

In 2007, a 9-year-old female blacktip shark at the Virginia Aquarium and Marine Science Center was found to be pregnant with a single near-term female pup, despite having never mated with a male. Genetic analysis confirmed that her offspring was the product of automictic parthenogenesis, a form of asexual reproduction in which an ovum merges with a polar body to form a zygote without fertilization. Along with an earlier case of parthenogenesis in the bonnethead (Sphyrna tiburo), this event suggests that asexual reproduction may be more widespread in sharks than previously thought.[31]

Human interactions

The blacktip shark usually poses little danger to divers.

Blacktip sharks showing curiosity towards divers has been reported, but they remain at a safe distance. Under most circumstances, these timid sharks are not regarded as highly dangerous to humans. However, they may become aggressive in the presence of food, and their size and speed invite respect.[1] As of 2008, the International Shark Attack File lists 28 unprovoked attacks (one fatal) and 13 provoked attacks by this species.[32] Blacktip sharks are responsible annually for 16% of the shark attacks around Florida. Most attacks by this species result in only minor wounds.[2]

As one of the most common large sharks in coastal waters, the blacktip shark is caught in large numbers by commercial fisheries throughout the world, using longlines, fixed-bottom nets, bottom trawls, and hook-and-line. The meat is of high quality and marketed fresh, frozen, or dried and salted. In addition, the fins are used for shark fin soup, the skin for leather, the liver oil for vitamins, and the carcasses for fishmeal.[1] Blacktip sharks are one of the most important species to the northwestern Atlantic shark fishery, second only to the sandbar shark (C. plumbeus). The flesh is considered superior to that of the sandbar shark, resulting in the sandbar and other requiem shark species being sold under the name "blacktip shark" in the United States. The blacktip shark is also very significant to Indian and Mexican fisheries, and is caught in varying numbers by fisheries in the Mediterranean and South China Seas, and off northern Australia.[28]

The blacktip shark is popular with recreational anglers in Florida, the Caribbean, and South Africa. It is listed as a game fish by the International Game Fish Association. Once hooked, this species is a strong, steady fighter that sometimes jumps out of the water.[2] Since 1995, the number of blacktip sharks taken by recreational anglers in the United States has approached or surpassed the number taken by commercial fishing.[28] The International Union for Conservation of Nature has assessed the blacktip shark as Near Threatened, as its low reproductive rate renders it vulnerable to overfishing.[33] The United States and Australia are the only two countries that manage fisheries catching blacktip sharks. In both cases, regulation occurs under umbrella management schemes for multiple shark species, such as that for the large coastal sharks category of the US National Marine Fisheries Service Atlantic shark Fisheries Management Plan. No conservation plans specifically for this species have been implemented.[28]

References

  1. ^ a b c d e f g h i j k l m n o Compagno, L.J.V. (1984). Sharks of the World: An Annotated and Illustrated Catalogue of Shark Species Known to Date. Rome: Food and Agricultural Organization. pp. 481–483. ISBN 92-5-101384-5. 
  2. ^ a b c d e f Curtis, T. Biological Profiles: Blacktip Shark. Florida Museum of Natural History Ichthyology Department. Retrieved on April 27, 2009.
  3. ^ a b c d Ebert, D.A. (2003). Sharks, Rays, and Chimaeras of California. London: University of California Press. pp. 156–157. ISBN 0-520-23484-7. 
  4. ^ a b c Froese, Rainer and Pauly, Daniel, eds. (2009). "Carcharhinus limbatus" in FishBase. April 2009 version.
  5. ^ Dosay-Akbulut, M. (2008). "The phylogenetic relationship within the genus Carcharhinus". Comptes Rendus Biologies. 331 (7): 500–509. PMID 18558373. doi:10.1016/j.crvi.2008.04.001. 
  6. ^ Keeney, D.B. & Heist, E.J. (October 2006). "Worldwide phylogeography of the blacktip shark (Carcharhinus limbatus) inferred from mitochondrial DNA reveals isolation of western Atlantic populations coupled with recent Pacific dispersal". Molecular Ecology. 15 (12): 3669–3679. PMID 17032265. doi:10.1111/j.1365-294X.2006.03036.x. 
  7. ^ Benson. R.N., ed. (1998). Geology and Paleontology of the Lower Miocene Pollack Farm Fossil Site, Delaware: Delaware Geological Survey Special Publication No. 21. Delaware Natural History Survey. pp. 133–139. 
  8. ^ Brown, R.C. (2008). Florida's Fossils: Guide to Location, Identification, and Enjoyment (third ed.). Pineapple Press Inc. p. 100. ISBN 1-56164-409-9. 
  9. ^ Martin, R.A. Albinism in Sharks. ReefQuest Centre for Shark Research. Retrieved on April 28, 2009.
  10. ^ Yano, Kazunari; Morrissey, John F. (1999-06-01). "Confirmation of blacktip shark,Carcharhinus limbatus, in the Ryukyu Islands and notes on possible absence ofC. melanopterus in Japanese waters". Ichthyological Research. 46 (2): 193–198. ISSN 1341-8998. doi:10.1007/BF02675438. 
  11. ^ a b c d e Castro, J.I. (November 1996). "Biology of the blacktip shark, Carcharhinus limbatus, off the southeastern United States". Bulletin of Marine Science. 59 (3): 508–522. 
  12. ^ Heupel, M.R. & Simpfendorfer, C.A. (2005). "Quantitative analysis of aggregation behavior in juvenile blacktip sharks". Marine Biology. 147 (5): 1239–1249. doi:10.1007/s00227-005-0004-7. 
  13. ^ Heupel, M.R. & Hueter, R.E. (2002). "The importance of prey density in relation to the movement patterns of juvenile sharks within a coastal nursery area". Marine and Freshwater Research. 53 (2): 543–550. doi:10.1071/MF01132. 
  14. ^ Bullard, S.A.; Frasca, A. (Jr.) & Benz, G.W. (June 2000). "Skin Lesions Caused by Dermophthirius penneri (Monogenea: Microbothriidae) on Wild-Caught Blacktip Sharks (Carcharhinus limbatus)". Journal of Parasitology. 86 (3): 618–622. PMID 10864264. doi:10.1645/0022-3395(2000)086[0618:SLCBDP]2.0.CO;2. 
  15. ^ Bullard, S.A.; Benz, G.W. & Braswell, J.S. (2000). "Dionchus postoncomiracidia (Monogenea: Dionchidae) from the skin of blacktip sharks, Carcharhinus limbatus (Carcharhinidae)". Journal of Parasitology. 86 (2): 245–250. JSTOR 3284763. PMID 10780540. doi:10.1645/0022-3395(2000)086[0245:DPMDFT]2.0.CO;2. 
  16. ^ Rosa-Molinar, E. & Williams, C.S. (1983). "Larval nematodes (Philometridae) in granulomas in ovaries of blacktip sharks, Carcharhinus limbatus (Valenciennes)". Journal of Wildlife Diseases. 19 (3): 275–277. PMID 6644926. doi:10.7589/0090-3558-19.3.275. 
  17. ^ Riner, E.K. & Brijnnschweiler, J.M. (2003). "Do sharksuckers, Echeneis naucrates, induce jump behaviour in blacktip sharks, Carcharhinus limbatus?". Marine and Freshwater Behaviour and Physiology. 36 (2): 111–113. doi:10.1080/1023624031000119584. 
  18. ^ Brunnschweiler, J.M. (2005). "Water-escape velocities in jumping blacktip sharks". Journal of the Royal Society Interface. 2 (4): 389–391. PMC 1578268Freely accessible. PMID 16849197. doi:10.1098/rsif.2005.0047. 
  19. ^ Ritter, E.K. & Godknecht, A.J. (February 1, 2000). Ross, S. T., ed. "Agonistic Displays in the Blacktip Shark (Carcharhinus limbatus)". Copeia. 2000 (1): 282–284. JSTOR 1448264. doi:10.1643/0045-8511(2000)2000[0282:ADITBS]2.0.CO;2. 
  20. ^ a b c Barry, K.P. (2002). Feeding habits of blacktip sharks, Carcharhinus limbatus, and Atlantic sharpnose sharks, Rhizoprionodon terraenovae, in Louisiana coastal waters. MS thesis, Louisiana State University, Baton Rouge.
  21. ^ Dudley, S.F.J. & Cliff, G. (1993). "Sharks caught in the protective gill nets off Natal, South Africa. 7. The blacktip shark Carcharhinus limbatus (Valenciennes)". African Journal of Marine Science. 13: 237–254. doi:10.2989/025776193784287356. 
  22. ^ a b Keeney, D.B.; Heupel, M.; Hueter, R.E. & Heist, E.J. (2003). "Genetic heterogeneity among blacktip shark, Carcharhinus limbatus, continental nurseries along the U.S. Atlantic and Gulf of Mexico". Marine Biology. 143 (6): 1039–1046. doi:10.1007/s00227-003-1166-9. 
  23. ^ Bornatowski, H. (2008). "A parturition and nursery area for Carcharhinus limbatus (Elasmobranchii, Carcharhinidae) off the coast of Paraná, Brazil". Brazilian Journal of Oceanography. 56 (4): 317–319. doi:10.1590/s1679-87592008000400008. 
  24. ^ Keeney, D.B.; Heupel, M.R.; Hueter, R.E. & Heist, E.J. (2005). "Microsatellite and mitochondrial DNA analyses of the genetic structure of blacktip shark (Carcharhinus limbatus) nurseries in the northwestern Atlantic, Gulf of Mexico, and Caribbean Sea". Molecular Ecology. 14 (7): 1911–1923. PMID 15910315. doi:10.1111/j.1365-294X.2005.02549.x. 
  25. ^ a b c Capapé, C.H.; Seck, A.A.; Diatta, Y.; Reynaud, C.H.; Hemida, F. & Zaouali, J. (2004). "Reproductive biology of the blacktip shark, Carcharhinus limbatus (Chondrichthyes: Carcharhinidae) off West and North African Coasts" (PDF). Cybium. 28 (4): 275–284. 
  26. ^ Heupel, M.R. & Simpfendorfer, C.A. (2002). "Estimation of mortality of juvenile blacktip sharks, Carcharhinus limbatus, within a nursery area using telemetry data". Canadian Journal of Fisheries and Aquatic Sciences. 59 (4): 624–632. doi:10.1139/f02-036. 
  27. ^ a b c Branstetter, S. (December 9, 1987). "Age and Growth Estimates for Blacktip, Carcharhinus limbatus, and Spinner, C. brevipinna, Sharks from the Northwestern Gulf of Mexico". Copeia. American Society of Ichthyologists and Herpetologists. 1987 (4): 964–974. JSTOR 1445560. doi:10.2307/1445560. 
  28. ^ a b c d Fowler, S.L.; Cavanagh, R.D.; Camhi, M.; Burgess, G.H.; Cailliet, G.M.; Fordham, S.V.; Simpfendorfer, C.A. & Musick, J.A. (2005). Sharks, Rays and Chimaeras: The Status of the Chondrichthyan Fishes. International Union for Conservation of Nature and Natural Resources. pp. 106–109, 293–295. ISBN 2-8317-0700-5. 
  29. ^ a b Killam, K.A. & Parsons, G.R. (May 1989). "Age and Growth of the Blacktip Shark, Carcharhinus limbatus, near Tampa Bay" (PDF). Florida Fishery Bulletin. 87: 845–857. 
  30. ^ Wintner, S.P. & Cliff, G. (1996). "Age and growth determination of the blacktip shark, Carcharhinus limbatus, from the east coast of South Africa" (PDF). Fishery Bulletin. 94 (1): 135–144. 
  31. ^ Chapman, D.D.; Firchau, B. & Shivji, M.S. (2008). "Parthenogenesis in a large-bodied requiem shark, the blacktip Carcharhinus limbatus". Journal of Fish Biology. 73 (6): 1473–1477. doi:10.1111/j.1095-8649.2008.02018.x. 
  32. ^ ISAF Statistics on Attacking Species of Shark. International Shark Attack File, Florida Museum of Natural History, University of Florida. Retrieved on April 22, 2009.
  33. ^ Musick, J.A.; Fowler, S. (2000). "Carcharhinus limbatus". IUCN Red List of Threatened Species. Version 2007. International Union for Conservation of Nature. Retrieved April 27, 2009. 
source: http://en.wikipedia.org/wiki/Blacktip_shark

Mexican Free-tailed Bat 2

Mexican Free-tailed Bat 2 by Inked Animal

Mexican Free-tailed Bat  | Tadarida brasiliensis

 

We found this Mexican Free-tailed bat, aka Brazilian Free-tailed bat, in Austin, Texas.  There are tons of these in the city under bridges and roof eves, Austin is known for the colony under the Congress bridge, which is apparently one of the biggest, if not the biggest, urban bat colonies in the world.  They are pretty impressive.

Mexican Free-tailed Bat info via Wikipedia:

Mexican free-tailed bat
Tadarida brasiliensis
Tadarida brasiliensis.jpg
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Chiroptera
Family: Molossidae
Genus: Tadarida
Species: T. brasiliensis
Binomial name
Tadarida brasiliensis
(I. Geoffroy, 1824)
Subspecies
  • T. b. antillularum
  • T. b. bahamensis
  • T. b. brasiliensis
  • T. b. constanzae
  • T. b. cynocephali
  • T. b. intermedia
  • T. b. mexicana
  • T. b. murina
  • T. b. muscula
Tadarida brasiliensis Range.png
Range of the Mexican free-tailed bat

The Mexican free-tailed bat or Brazilian free-tailed bat (Tadarida brasiliensis) is a medium-sized bat that is native to the Americas, regarded as one of the most abundant mammals in North America. Its proclivity towards roosting in huge numbers at relatively few locations makes it vulnerable to habitat destruction in spite of its abundance. The bat is considered a species of special concern in California as a result of declining populations. It has been claimed to have the fastest horizontal speed (as opposed to stoop diving speed) of any animal, reaching top ground speeds of over 160 km/h; its actual air speed has not been measured.

Taxonomy

Molecular sequence data indicates T. brasiliensis's closest relatives are Chaerephon jobimena of Madagascar and Tadarida aegyptiaca of Africa and south Asia; the latter two are sister species. These three species form a clade believed to be about 9.8 million years old.[2]

Physical description

Mexican free-tailed bats are on average 9 cm (3.5 in) in length and weigh approximately 12.3 g (0.43 oz). The average wingspan is 28 cm (11 in).[3] Their tail is almost half their total length and stretches beyond the uropatagium, giving them the name "free-tailed" bats. Their ears are relatively close behind the muzzle and eyes; they are wide and set apart to help them find prey using echolocation. The muzzle is condensed, with wrinkled upper lips. The wings are elongated and narrow with pointed tips, making them well-equipped for quick, straight flight patterns. Their fur color ranges from dark brown to gray. The Mexican free-tailed bat's large feet have distinct long, white bristles. [4][5]

Range and ecology

Bats flying near Frio Cave in Concan, Texas

The Mexican free-tailed bat ranges from the southern half of the continental United States through most of Mexico, and through most of Central America into South America. The range of the Mexican free-tailed bat in South America is less understood where it lives in the eastern Brazilian highlands and coast, the northeastern Andes and the coast of Peru and northern Chile.[6] It is absent in much of the Amazon rainforest. The bat is also found in the Caribbean, and is native to all of the Greater Antilles and 11 of the Lesser Antilles.[7] The largest known colony is found at Bracken Cave, north of San Antonio, Texas, with nearly 20 million bats; research indicates the bats from this colony congregate in huge numbers at altitudes between 180 and 1,000 m (590 and 3,280 ft), and even as high as 3,000 m (9,800 ft).

Habitat

Mexican free-tailed bats roost primarily in caves. However, they will also roost in buildings of any type as long as they have access to openings and dark recesses in ceilings or walls.[6] The bats can make roosting sites of buildings regardless of "age, height, architecture, construction materials, occupancy by humans and compass orientation".[6] Caves, on the other hand, need to have enough wall and ceiling space to fit millions of bats.[6] Before buildings, free-tailed bats in the southeastern United States probably roosted in the hollows of trees such as red mangrove, black mangrove, white mangrove and cypress. However, most bats in Florida seem to prefer buildings and other man-made structures over natural roosts.[6] Caves in Florida tend to be occupied mostly by the southeastern myotis. Caves in Florida tend to have pools of water on the floor and the free-tailed bats do not need as much relative humidity as the southeastern myotis.[6]

Migration

Mexican free-tailed bats, emerging from Carlsbad Caverns, Carlsbad Caverns National Park, New Mexico

Mexican free-tailed bats in southeastern Nevada, southwestern Utah, western Arizona and southeastern California come together to migrate southwest to southern California and Baja California.[6] Bats in southeastern Utah, southwestern Colorado, western New Mexico and eastern Arizona travel though western edge of the Sierra Madre Oriental into Jalisco, Sinaloa and Sonora. Some bats that summer in Kansas, Oklahoma, eastern New Mexico and Texas will migrate southward to southern Texas[8] and Mexico.[6] Some bat populations in other areas of North America do not migrate, but are residents and may make seasonal changes in roost sites.[6]

Dusk emergence of bats at the Congress Avenue Bridge in Austin, Texas, U.S.

In Austin, Texas, a colony of Mexican free-tailed bats summers (they winter in Mexico) under the Congress Avenue Bridge ten blocks south of the Texas State Capitol. It is the largest urban colony in North America, with an estimated 1,500,000 bats.[9] Each night they eat 10,000 to 30,000 lb (4,500 to 13,600 kg) of insects. Each year they attract 100,000 tourists who come to watch them. In Houston, Texas, a colony is living under the Waugh Street Bridge over Buffalo Bayou. It is the home to 250,000 bats and also attracts viewers. The Mexican free-tailed bat is the official flying mammal of the state of Texas.[10]

Bats ranging eastward from East Texas do not migrate, but local shifts in roost usage often occur seasonally.[6] Also, a regional population that ranges from Oregon to California, has a year-round residence.

Diet

The Mexican free-tailed bat features in the logo of the Bacardi company

Mexican free-tailed bats are primarily insectivores. They hunt their prey using echolocation. The bats eat moths, beetles, dragonflies, flies, true bugs, wasps, and ants. Bats usually catch flying prey in flight.[11] Large numbers of Mexican free-tailed bats fly hundreds of meters above the ground in Texas to feed on migrating insects.[12] The consumption of insects by these bats can be quite significant.[13][14]

Health and mortality

One individual bat was recorded to have lived eight years, based on dentition.[15] Predators of the bat include large birds such as red-tailed hawk, American kestrels, great horned owls, barn owls, and Mississippi kites.[6][16] Mammal predators include Virginia opossums, striped skunks, and raccoons.[6] Snakes such as eastern coachwhips and eastern coral snakes may also prey on them, but at a lesser extent. Certain types of beetles prey on neonate and juvenile bats that have fallen to the ground.[6] This species seems to have a low incidence of rabies, at least in the United States.[6] They do, however, contain certain pesticides.[6]

Behavior

A male displays and sings in the presence of females (watch in slow motion).

Mexican free-tailed bats are nocturnal foragers and begin feeding after dusk. They travel 50 km in a quick, direct flight pattern to feed. This species flies the highest among bats, at altitudes around 3300 m.[17] Bats appear to be most active in late morning and afternoon between June and September.[18] Free-tailed bats are more active in warm weather.[19]

The species has been measured at a ground speed of 160 kilometres per hour (99 mph), measured by an aircraft tracking device.[20] The measurement methodology did not simultaneously record wind speed and ground speed, so the observations could have been affected by strong local gusts, and the bat's maximum air speed remains uncertain.[21]

Echolocation

Mexican free-tailed bats use echolocation for navigation and detecting prey. Traveling calls are of a brief but constant frequency. However, they switch modulated frequency calls between 40 and 75 kHz if they detect something.[22] Typically, the frequency range of their echolocation is between 49 and 70 kHz, but can be between 25 and 40 kHz if something crosses their path while in flight.[22]

On 6 November 2014, Aaron Corcoran, a biologist at Wake Forest University, North Carolina, reported online in Science that he and his team had detected Mexican free-tailed bats emitting ultrasonic vocalizations which had the effect of jamming the echolocation calls of a rival bat species hunting moths. The ‘jamming’ call led to an increased chance of the rival missing its prey, which the Mexican free-tailed bat was then able to eat itself. Earlier researchers had discovered some 15 types of social calls made by Mexican free-tailed bats and reported that they could adjust their calls to avoid interfering with others in range of their calls.[23][24]

Mating and reproduction

Free-tailed bats roosting at a cave in the Bahamas

During the breeding season, females aggregate into maternity roosts. The size of these roosts depends on the environment, with caves having the larger roosts. Mating can occur in an aggressive or passive form. In the aggressive form, the male controls the female's movements, keeping her away from the other bats in the roost.[25] He also tends to vocalize when mating. During passive copulation, the males simply flies to a female in her roost and quietly mounts her with no resistance. This species is a promiscuous breeder and both sexes copulate with multiple partners.[25] Females become sexually mature at about 9 months, while males take even longer, at two years. Females enter estrus once a year, which typically lasts five weeks in the spring. The gestation period of the bat lasts 11–12 weeks, with only one young being born. A number of pups are left in "creches", while their mothers roost elsewhere. The female uses vocalizations and scent to identify her pup. The mother imprints her scent on the young early on.[26] However, young try to steal a suckle from any female that passes through the cluster. A mother will nurse her young daily, and by 4–7 weeks old they are full grown, fully weaned, and independent.[27]

Protection

Though abundant and widespread, some local populations have prompted protection and conservation efforts. For instance, during the spring and summer, one of the largest Mexican free-tailed bat populations inhabits Cueva de la Boca, a cave near Monterrey, Mexico. In 2006, the Mexican environmental conservation NGO, Pronatura Noreste, purchased the property. Because of a reduction of more than 95% of the original 20 million bat population, as a result of vandalism, pollution, and uncontrolled tourism, the organization decided to buy the property to place it under conservation. Other species of high ecological value that inhabit the cavern are also being protected.

See also

  • Bat bomb, an experimental incendiary weapon that used Mexican free-tailed bats as a dispersal mechanism

References

  1. ^ Barquez, R., Diaz, M., Gonzalez, E., Rodriguez, A., Incháustegui, S. & Arroyo-Cabrales, J. (2015). Tadarida brasiliensis. The IUCN Red List of Threatened Species doi:10.2305/IUCN.UK.2015-4.RLTS.T21314A22121621.en
  2. ^ Lamb, J. M.; Ralph, T. M. C.; Naidoo, T.; Taylor, P. J.; Ratrimomanarivo, F.; Stanley, W. T.; Goodman, S. M. (June 2011). "Toward a Molecular Phylogeny for the Molossidae (Chiroptera) of the Afro-Malagasy Region". Acta Chiropterologica. 13 (1): 1–16. doi:10.3161/150811011X578589. 
  3. ^ "Animal Diversity Web: Tadarida brasiliensis". Retrieved 2016-11-10. 
  4. ^ http://www.nsrl.ttu.edu/tmot1/tadabras.htm
  5. ^ https://upload.wikimedia.org/wikipedia/commons/b/b9/Mexican_free-tailed_bat_%288006850693%29.jpg
  6. ^ a b c d e f g h i j k l m n o Wilkins, K. (1989). "Tadarida brasiliensis" (PDF). Mammalian Species. 331: 1–10. 
  7. ^ Baker, R. J., Genoways, H. H. (1978). "Zoogeography of Antillean bats", pp. 53–97 in Zoogeography in the Caribbean, F. B. Gill (ed.). Philadelphia: Acad
  8. ^ Glass BP (1982). "Seasonal movements of Mexican free-tail bats Tadarida brasiliensis mextcana banded in the Great Plains". Southwestern Nat. 27: 127–133. 
  9. ^ "Congress Avenue Bridge". Congress Avenue Bridge Bat Colony. Archived from the original on 12 November 2008. CS1 maint: BOT: original-url status unknown (link)
  10. ^ "Texas State Symbols". Texas State Library and Archives Commission. 
  11. ^ McWilliams, Lisa A. (2005). "Variation in Diet of the Mexican Free-Tailed Bat (Tadarida brasiliensis mexicana)". Journal of Mammalogy. 86 (3): 599. doi:10.1644/1545-1542(2005)86[599:VIDOTM]2.0.CO;2. 
  12. ^ McCracken, G. F.; Gillam, E. H.; Westbrook, J. K.; Lee, Y. F.; Jensen, M. L.; Balsley, B. B. (2008). "Brazilian free-tailed bats (Tadarida brasiliensis: Molossidae, Chiroptera) at high altitude: Links to migratory insect populations". Integrative and Comparative Biology. 48 (1): 107–18. PMID 21669777. doi:10.1093/icb/icn033. 
  13. ^ Corrigan, Robert. Do Bats Control Mosquitoes? texasmosquito.org
  14. ^ Animal Fact Sheet: Mexican Free-Tailed Bat. Desert Museum
  15. ^ Gannon, M., A. Kurta, A. Rodriquez-Duran, M. Willig. (2005). Bats of Puerto Rico. Jamaica. The University of the West Indies Press.
  16. ^ Mikula, P.; Morelli, F.; Lučan, R. K.; Jones, D. N.; Tryjanowski, P. (2016). "Bats as prey of diurnal birds: a global perspective". Mammal Review. 46 (3): 160. doi:10.1111/mam.12060. 
  17. ^ Williams, T. C.; Ireland, L. C.; Williams, J. M. (1973). "High Altitude Flights of the Free-Tailed Bat, Tadarida brasiliensis, Observed with Radar". Journal of Mammalogy. 54 (4): 807. JSTOR 1379076. doi:10.2307/1379076. 
  18. ^ Svoboda, P. L.; Choate, J. R. (1987). "Natural History of the Brazilian Free-Tailed Bat in the San Luis Valley of Colorado". Journal of Mammalogy. 68 (2): 224. JSTOR 1381461. doi:10.2307/1381461. 
  19. ^ Allen, L. C.; Turmelle, A. S.; Mendonça, M. T.; Navara, K. J.; Kunz, T. H.; McCracken, G. F. (2009). "Roosting ecology and variation in adaptive and innate immune system function in the Brazilian free-tailed bat (Tadarida brasiliensis)" (PDF). Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology. 179 (3): 315–23. PMID 19002470. doi:10.1007/s00360-008-0315-3. 
  20. ^ McCracken, Gary F.; Safi, Kamran; Kunz, Thomas H.; Dechmann, Dina K. N.; Swartz, Sharon M.; Wikelski, Martin (9 November 2016). "Airplane tracking documents the fastest flight speeds recorded for bats". Royal Society Open Science. 3 (11): 160398. doi:10.1098/rsos.160398. 
  21. ^ Photopoulos, Julianna (9 November 2016). "Speedy bat flies at 160km/h, smashing bird speed record". New Scientist. Retrieved 11 November 2016. But not everyone is convinced. Graham Taylor at the University of Oxford says that errors in estimating bat speed by measuring the distance moved between successive positions could be huge. “So I think it would be premature to knock birds off their pedestal as nature's fastest fliers just yet,” he says."These bats are indeed flying very fast at times, but this is based on their ground speed," says Anders Hedenström at the University of Lund in Sweden. "Since they did not measure winds at the place and time where the bats are flying, one can therefore not exclude that the top speeds are not bats flying in a gust." 
  22. ^ a b Gillam, Erin H.; McCracken, Gary F. (2007). "Variability in the echolocation of Tadarida brasiliensis: Effects of geography and local acoustic environment". Animal Behaviour. 74 (2): 277. doi:10.1016/j.anbehav.2006.12.006. 
  23. ^ Morell, Virginia (6 November 2014). "Holy blocked bat signal! Bats jam each other's calls". new.sciencemag.org. Retrieved 8 November 2014. 
  24. ^ Hogenboom, Melissa (7 November 2014). "Bats sabotage rivals' senses with sound in food race". BBC News. Retrieved 8 November 2014. 
  25. ^ a b Keeley, Annika T. H.; Keeley, Brian W. (2004). "The Mating System of Tadarida brasiliensis (Chiroptera: Molossidae) in a Large Highway Bridge Colony". Journal of Mammalogy. 85: 113. doi:10.1644/BME-004. 
  26. ^ Loughry, W. J.; McCracken, G. F. (1991). "Factors Influencing Female-Pup Scent Recognition in Mexican Free-Tailed Bats". Journal of Mammalogy. 72 (3): 624. JSTOR 1382150. doi:10.2307/1382150. 
  27. ^ Kunz, Thomas H.; Robson, Simon K. (1995). "Postnatal Growth and Development in the Mexican Free-Tailed Bat (Tadarida brasiliensis mexicana): Birth Size, Growth Rates, and Age Estimation" (PDF). Journal of Mammalogy. 76 (3): 769. JSTOR 1382746. doi:10.2307/1382746. 
source: http://en.wikipedia.org/wiki/Mexican_Free-tailed_Bat

Mexican Free-tailed Bat 1

Mexican Free-tailed Bat, Tadarida brasiliensis by Inked Animal

Mexican Free-tailed Bat  | Tadarida brasiliensis

We found this Mexican Free-tailed bat, aka Brazilian Free-tailed bat, in Austin, Texas.  There are tons of these in the city under bridges and roof eves, Austin is known for the colony under the Congress bridge, which is apparently one of the biggest, if not the biggest, urban bat colonies in the world.  They are pretty impressive.

   


Mexican Free-tailed Bat info via Wikipedia:

Mexican free-tailed bat
Tadarida brasiliensis
Tadarida brasiliensis.jpg
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Chiroptera
Family: Molossidae
Genus: Tadarida
Species: T. brasiliensis
Binomial name
Tadarida brasiliensis
(I. Geoffroy, 1824)
Subspecies
  • T. b. antillularum
  • T. b. bahamensis
  • T. b. brasiliensis
  • T. b. constanzae
  • T. b. cynocephali
  • T. b. intermedia
  • T. b. mexicana
  • T. b. murina
  • T. b. muscula
Tadarida brasiliensis Range.png
Range of the Mexican free-tailed bat

The Mexican free-tailed bat or Brazilian free-tailed bat (Tadarida brasiliensis) is a medium-sized bat that is native to the Americas, regarded as one of the most abundant mammals in North America. Its proclivity towards roosting in huge numbers at relatively few locations makes it vulnerable to habitat destruction in spite of its abundance. The bat is considered a species of special concern in California as a result of declining populations. It has been claimed to have the fastest horizontal speed (as opposed to stoop diving speed) of any animal, reaching top ground speeds of over 160 km/h; its actual air speed has not been measured.

Taxonomy

Molecular sequence data indicates T. brasiliensis's closest relatives are Chaerephon jobimena of Madagascar and Tadarida aegyptiaca of Africa and south Asia; the latter two are sister species. These three species form a clade believed to be about 9.8 million years old.[2]

Physical description

Mexican free-tailed bats are on average 9 cm (3.5 in) in length and weigh approximately 12.3 g (0.43 oz). The average wingspan is 28 cm (11 in).[3] Their tail is almost half their total length and stretches beyond the uropatagium, giving them the name "free-tailed" bats. Their ears are relatively close behind the muzzle and eyes; they are wide and set apart to help them find prey using echolocation. The muzzle is condensed, with wrinkled upper lips. The wings are elongated and narrow with pointed tips, making them well-equipped for quick, straight flight patterns. Their fur color ranges from dark brown to gray. The Mexican free-tailed bat's large feet have distinct long, white bristles. [4][5]

Range and ecology

Bats flying near Frio Cave in Concan, Texas

The Mexican free-tailed bat ranges from the southern half of the continental United States through most of Mexico, and through most of Central America into South America. The range of the Mexican free-tailed bat in South America is less understood where it lives in the eastern Brazilian highlands and coast, the northeastern Andes and the coast of Peru and northern Chile.[6] It is absent in much of the Amazon rainforest. The bat is also found in the Caribbean, and is native to all of the Greater Antilles and 11 of the Lesser Antilles.[7] The largest known colony is found at Bracken Cave, north of San Antonio, Texas, with nearly 20 million bats; research indicates the bats from this colony congregate in huge numbers at altitudes between 180 and 1,000 m (590 and 3,280 ft), and even as high as 3,000 m (9,800 ft).

Habitat

Mexican free-tailed bats roost primarily in caves. However, they will also roost in buildings of any type as long as they have access to openings and dark recesses in ceilings or walls.[6] The bats can make roosting sites of buildings regardless of "age, height, architecture, construction materials, occupancy by humans and compass orientation".[6] Caves, on the other hand, need to have enough wall and ceiling space to fit millions of bats.[6] Before buildings, free-tailed bats in the southeastern United States probably roosted in the hollows of trees such as red mangrove, black mangrove, white mangrove and cypress. However, most bats in Florida seem to prefer buildings and other man-made structures over natural roosts.[6] Caves in Florida tend to be occupied mostly by the southeastern myotis. Caves in Florida tend to have pools of water on the floor and the free-tailed bats do not need as much relative humidity as the southeastern myotis.[6]

Migration

Mexican free-tailed bats, emerging from Carlsbad Caverns, Carlsbad Caverns National Park, New Mexico

Mexican free-tailed bats in southeastern Nevada, southwestern Utah, western Arizona and southeastern California come together to migrate southwest to southern California and Baja California.[6] Bats in southeastern Utah, southwestern Colorado, western New Mexico and eastern Arizona travel though western edge of the Sierra Madre Oriental into Jalisco, Sinaloa and Sonora. Some bats that summer in Kansas, Oklahoma, eastern New Mexico and Texas will migrate southward to southern Texas[8] and Mexico.[6] Some bat populations in other areas of North America do not migrate, but are residents and may make seasonal changes in roost sites.[6]

Dusk emergence of bats at the Congress Avenue Bridge in Austin, Texas, U.S.

In Austin, Texas, a colony of Mexican free-tailed bats summers (they winter in Mexico) under the Congress Avenue Bridge ten blocks south of the Texas State Capitol. It is the largest urban colony in North America, with an estimated 1,500,000 bats.[9] Each night they eat 10,000 to 30,000 lb (4,500 to 13,600 kg) of insects. Each year they attract 100,000 tourists who come to watch them. In Houston, Texas, a colony is living under the Waugh Street Bridge over Buffalo Bayou. It is the home to 250,000 bats and also attracts viewers. The Mexican free-tailed bat is the official flying mammal of the state of Texas.[10]

Bats ranging eastward from East Texas do not migrate, but local shifts in roost usage often occur seasonally.[6] Also, a regional population that ranges from Oregon to California, has a year-round residence.

Diet

The Mexican free-tailed bat features in the logo of the Bacardi company

Mexican free-tailed bats are primarily insectivores. They hunt their prey using echolocation. The bats eat moths, beetles, dragonflies, flies, true bugs, wasps, and ants. Bats usually catch flying prey in flight.[11] Large numbers of Mexican free-tailed bats fly hundreds of meters above the ground in Texas to feed on migrating insects.[12] The consumption of insects by these bats can be quite significant.[13][14]

Health and mortality

One individual bat was recorded to have lived eight years, based on dentition.[15] Predators of the bat include large birds such as red-tailed hawk, American kestrels, great horned owls, barn owls, and Mississippi kites.[6][16] Mammal predators include Virginia opossums, striped skunks, and raccoons.[6] Snakes such as eastern coachwhips and eastern coral snakes may also prey on them, but at a lesser extent. Certain types of beetles prey on neonate and juvenile bats that have fallen to the ground.[6] This species seems to have a low incidence of rabies, at least in the United States.[6] They do, however, contain certain pesticides.[6]

Behavior

A male displays and sings in the presence of females (watch in slow motion).

Mexican free-tailed bats are nocturnal foragers and begin feeding after dusk. They travel 50 km in a quick, direct flight pattern to feed. This species flies the highest among bats, at altitudes around 3300 m.[17] Bats appear to be most active in late morning and afternoon between June and September.[18] Free-tailed bats are more active in warm weather.[19]

The species has been measured at a ground speed of 160 kilometres per hour (99 mph), measured by an aircraft tracking device.[20] The measurement methodology did not simultaneously record wind speed and ground speed, so the observations could have been affected by strong local gusts, and the bat's maximum air speed remains uncertain.[21]

Echolocation

Mexican free-tailed bats use echolocation for navigation and detecting prey. Traveling calls are of a brief but constant frequency. However, they switch modulated frequency calls between 40 and 75 kHz if they detect something.[22] Typically, the frequency range of their echolocation is between 49 and 70 kHz, but can be between 25 and 40 kHz if something crosses their path while in flight.[22]

On 6 November 2014, Aaron Corcoran, a biologist at Wake Forest University, North Carolina, reported online in Science that he and his team had detected Mexican free-tailed bats emitting ultrasonic vocalizations which had the effect of jamming the echolocation calls of a rival bat species hunting moths. The ‘jamming’ call led to an increased chance of the rival missing its prey, which the Mexican free-tailed bat was then able to eat itself. Earlier researchers had discovered some 15 types of social calls made by Mexican free-tailed bats and reported that they could adjust their calls to avoid interfering with others in range of their calls.[23][24]

Mating and reproduction

Free-tailed bats roosting at a cave in the Bahamas

During the breeding season, females aggregate into maternity roosts. The size of these roosts depends on the environment, with caves having the larger roosts. Mating can occur in an aggressive or passive form. In the aggressive form, the male controls the female's movements, keeping her away from the other bats in the roost.[25] He also tends to vocalize when mating. During passive copulation, the males simply flies to a female in her roost and quietly mounts her with no resistance. This species is a promiscuous breeder and both sexes copulate with multiple partners.[25] Females become sexually mature at about 9 months, while males take even longer, at two years. Females enter estrus once a year, which typically lasts five weeks in the spring. The gestation period of the bat lasts 11–12 weeks, with only one young being born. A number of pups are left in "creches", while their mothers roost elsewhere. The female uses vocalizations and scent to identify her pup. The mother imprints her scent on the young early on.[26] However, young try to steal a suckle from any female that passes through the cluster. A mother will nurse her young daily, and by 4–7 weeks old they are full grown, fully weaned, and independent.[27]

Protection

Though abundant and widespread, some local populations have prompted protection and conservation efforts. For instance, during the spring and summer, one of the largest Mexican free-tailed bat populations inhabits Cueva de la Boca, a cave near Monterrey, Mexico. In 2006, the Mexican environmental conservation NGO, Pronatura Noreste, purchased the property. Because of a reduction of more than 95% of the original 20 million bat population, as a result of vandalism, pollution, and uncontrolled tourism, the organization decided to buy the property to place it under conservation. Other species of high ecological value that inhabit the cavern are also being protected.

See also

  • Bat bomb, an experimental incendiary weapon that used Mexican free-tailed bats as a dispersal mechanism

References

  1. ^ Barquez, R., Diaz, M., Gonzalez, E., Rodriguez, A., Incháustegui, S. & Arroyo-Cabrales, J. (2015). Tadarida brasiliensis. The IUCN Red List of Threatened Species doi:10.2305/IUCN.UK.2015-4.RLTS.T21314A22121621.en
  2. ^ Lamb, J. M.; Ralph, T. M. C.; Naidoo, T.; Taylor, P. J.; Ratrimomanarivo, F.; Stanley, W. T.; Goodman, S. M. (June 2011). "Toward a Molecular Phylogeny for the Molossidae (Chiroptera) of the Afro-Malagasy Region". Acta Chiropterologica. 13 (1): 1–16. doi:10.3161/150811011X578589. 
  3. ^ "Animal Diversity Web: Tadarida brasiliensis". Retrieved 2016-11-10. 
  4. ^ http://www.nsrl.ttu.edu/tmot1/tadabras.htm
  5. ^ https://upload.wikimedia.org/wikipedia/commons/b/b9/Mexican_free-tailed_bat_%288006850693%29.jpg
  6. ^ a b c d e f g h i j k l m n o Wilkins, K. (1989). "Tadarida brasiliensis" (PDF). Mammalian Species. 331: 1–10. 
  7. ^ Baker, R. J., Genoways, H. H. (1978). "Zoogeography of Antillean bats", pp. 53–97 in Zoogeography in the Caribbean, F. B. Gill (ed.). Philadelphia: Acad
  8. ^ Glass BP (1982). "Seasonal movements of Mexican free-tail bats Tadarida brasiliensis mextcana banded in the Great Plains". Southwestern Nat. 27: 127–133. 
  9. ^ "Congress Avenue Bridge". Congress Avenue Bridge Bat Colony. Archived from the original on 12 November 2008. CS1 maint: BOT: original-url status unknown (link)
  10. ^ "Texas State Symbols". Texas State Library and Archives Commission. 
  11. ^ McWilliams, Lisa A. (2005). "Variation in Diet of the Mexican Free-Tailed Bat (Tadarida brasiliensis mexicana)". Journal of Mammalogy. 86 (3): 599. doi:10.1644/1545-1542(2005)86[599:VIDOTM]2.0.CO;2. 
  12. ^ McCracken, G. F.; Gillam, E. H.; Westbrook, J. K.; Lee, Y. F.; Jensen, M. L.; Balsley, B. B. (2008). "Brazilian free-tailed bats (Tadarida brasiliensis: Molossidae, Chiroptera) at high altitude: Links to migratory insect populations". Integrative and Comparative Biology. 48 (1): 107–18. PMID 21669777. doi:10.1093/icb/icn033. 
  13. ^ Corrigan, Robert. Do Bats Control Mosquitoes? texasmosquito.org
  14. ^ Animal Fact Sheet: Mexican Free-Tailed Bat. Desert Museum
  15. ^ Gannon, M., A. Kurta, A. Rodriquez-Duran, M. Willig. (2005). Bats of Puerto Rico. Jamaica. The University of the West Indies Press.
  16. ^ Mikula, P.; Morelli, F.; Lučan, R. K.; Jones, D. N.; Tryjanowski, P. (2016). "Bats as prey of diurnal birds: a global perspective". Mammal Review. 46 (3): 160. doi:10.1111/mam.12060. 
  17. ^ Williams, T. C.; Ireland, L. C.; Williams, J. M. (1973). "High Altitude Flights of the Free-Tailed Bat, Tadarida brasiliensis, Observed with Radar". Journal of Mammalogy. 54 (4): 807. JSTOR 1379076. doi:10.2307/1379076. 
  18. ^ Svoboda, P. L.; Choate, J. R. (1987). "Natural History of the Brazilian Free-Tailed Bat in the San Luis Valley of Colorado". Journal of Mammalogy. 68 (2): 224. JSTOR 1381461. doi:10.2307/1381461. 
  19. ^ Allen, L. C.; Turmelle, A. S.; Mendonça, M. T.; Navara, K. J.; Kunz, T. H.; McCracken, G. F. (2009). "Roosting ecology and variation in adaptive and innate immune system function in the Brazilian free-tailed bat (Tadarida brasiliensis)" (PDF). Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology. 179 (3): 315–23. PMID 19002470. doi:10.1007/s00360-008-0315-3. 
  20. ^ McCracken, Gary F.; Safi, Kamran; Kunz, Thomas H.; Dechmann, Dina K. N.; Swartz, Sharon M.; Wikelski, Martin (9 November 2016). "Airplane tracking documents the fastest flight speeds recorded for bats". Royal Society Open Science. 3 (11): 160398. doi:10.1098/rsos.160398. 
  21. ^ Photopoulos, Julianna (9 November 2016). "Speedy bat flies at 160km/h, smashing bird speed record". New Scientist. Retrieved 11 November 2016. But not everyone is convinced. Graham Taylor at the University of Oxford says that errors in estimating bat speed by measuring the distance moved between successive positions could be huge. “So I think it would be premature to knock birds off their pedestal as nature's fastest fliers just yet,” he says."These bats are indeed flying very fast at times, but this is based on their ground speed," says Anders Hedenström at the University of Lund in Sweden. "Since they did not measure winds at the place and time where the bats are flying, one can therefore not exclude that the top speeds are not bats flying in a gust." 
  22. ^ a b Gillam, Erin H.; McCracken, Gary F. (2007). "Variability in the echolocation of Tadarida brasiliensis: Effects of geography and local acoustic environment". Animal Behaviour. 74 (2): 277. doi:10.1016/j.anbehav.2006.12.006. 
  23. ^ Morell, Virginia (6 November 2014). "Holy blocked bat signal! Bats jam each other's calls". new.sciencemag.org. Retrieved 8 November 2014. 
  24. ^ Hogenboom, Melissa (7 November 2014). "Bats sabotage rivals' senses with sound in food race". BBC News. Retrieved 8 November 2014. 
  25. ^ a b Keeley, Annika T. H.; Keeley, Brian W. (2004). "The Mating System of Tadarida brasiliensis (Chiroptera: Molossidae) in a Large Highway Bridge Colony". Journal of Mammalogy. 85: 113. doi:10.1644/BME-004. 
  26. ^ Loughry, W. J.; McCracken, G. F. (1991). "Factors Influencing Female-Pup Scent Recognition in Mexican Free-Tailed Bats". Journal of Mammalogy. 72 (3): 624. JSTOR 1382150. doi:10.2307/1382150. 
  27. ^ Kunz, Thomas H.; Robson, Simon K. (1995). "Postnatal Growth and Development in the Mexican Free-Tailed Bat (Tadarida brasiliensis mexicana): Birth Size, Growth Rates, and Age Estimation" (PDF). Journal of Mammalogy. 76 (3): 769. JSTOR 1382746. doi:10.2307/1382746. 
source: http://en.wikipedia.org/wiki/Mexican_Free-tailed_Bat

Roof Rat

Mouse print in style of Gyotaku

 Roof Rat | Rattus rattus


Redbreast Sunfish

Redbreast Sunfish Gyotaku by Inked Animal

Redbreast Sunfish | Lepomis auritus

 

 


 

Redbreast Sunfish info via Wikipedia:

Redbreast sunfish
Lepomis auritus.jpg
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Perciformes
Family: Centrarchidae
Genus: Lepomis
Species: L. auritus
Binomial name
Lepomis auritus
(Linnaeus, 1758)

The redbreast sunfish (Lepomis auritus) is a species of freshwater fish in the sunfish family (family Centrarchidae) of order Perciformes. The type species of its genus, it is native to the river systems of eastern Canada and the United States. The redbreast sunfish reaches a maximum recorded length of about 30 cm (12 in), with a maximum recorded weight of 790 g (1.7 lb).

The species prefers vegetated and rocky pools and lake margins for its habitat. Its diet can include insects, snails, and other small invertebrates. A panfish popular with anglers, the redbreast sunfish is also kept as an aquarium fish by hobbyists. Redbreast sunfish are usually caught with live bait such as nightcrawlers, crickets, grasshoppers, waxworms, or mealworms. They can also be caught using small lures or flies. Most anglers use light spinning tackle to catch redbreast sunfish. It is popular with fly anglers in the winter because it will more readily strike a moving fly than will bluegills in cooler water.

As is typical for the sunfishes, the female redbreast sunfish lays her eggs (about 1000) in a substrate depression built by the male. The male guards the eggs and fry.

Lepomis auritus has been transplanted to and become established in Germany, Italy, Mexico, and Puerto Rico, sometimes with a harmful effect on native species.

The specific epithet, auritus, is Latin for big-eared.

Typical redbreast sunfish from the Tallapoosa River, Alabama (released)

Description

Redbreasted Sunfish - Lepomis auritus from Maryland
Redbreast Sunfish Caught on 1/8oz Rooster Tail in Georgia

The species native range is condensed to eastern North America, in Canada and south to the rivers emptying into the Atlantic Ocean. The species has been introduced as far west as Texas. This fish primarily feeds on small insect larva, small crayfish, and sometimes small fish. Lepomis auritus thrives in streams and rivers with shelter and structure, usually around banks with the water pH around 7.0-7.5. The redbreast sunfish is a spring spawner in sand-gravel substrate depending on location, or when water temperatures reach 16-26 °C. Average clutch size for the sunfish is around 2000 depending on the age of the female. The average length of the sunfish is around 11 cm with a record 30.5 cm. The record weight for the fish is 1.75 pounds. Rarely are limits set on the number of fish that can be harvested due to their large numbers and high reproductive capabilities. If a particular area is subject to overfishing or habitat destruction, managements plans should be put into effect to preserve the population.

Distribution

The redbreasted sunfish tends to be more of a cool-river species, but also inhabits freshwater lakes and streams. The species has been introduced as far west as Louisiana and West Texas. Native range of the sunfish is a relatively large area with the species new introduction points not straying far from its native habitats.

Ecology

Redbreast sunfish mainly consume immature aquatic insects. Mayflies, small fish, and dragonfly larvae consist of the majority of the sunfish’s diet based on stomach content. Being an opportunistic feeder, the fish competes with other sunfish and larger predatory fish that prey on the same food they do. Larger piscivorous fish are the main predators of smaller redbreast sunfish. Micropterus species are a major threat to sunfish because of the shared habitat and the large availability of the sunfish. The sunfish prefers structure around banks and overhanging branches that provide shade to provide food and protection. Lepomis auritus survives best in water with current and a pH between 7.0 and 7.5. Lack of current or too acidic or basic water can dramatically affect the sunfish’s survival rate. Human influence on abiotic and biotic factors such as sunlight and predator numbers can have a major influence on sunfish. Factors such as clearing debris bank cover can increase amount of sunlight into the water and increase water temperature and decrease defense habitats, also decreasing the number of predators by eating larger predatory fish will increase the survival rate of the redbreast sunfish.

Life history

The redbreast sunfish is a fall spawner on sand-gravel substrate depending on location, or when water temperature reaches 16-26 °C. According to Stanley Sharp, “The mature male generally builds a nest in shallow water or may simply use the abandoned nest of another Centrarchid. The female eventually enters the nest, releases her adhesive eggs, and then leaves. The male remains to guard and fan the eggs and possibly even to guard the young for a brief period. The male and female will then move out of the shallow water after spawning and into deeper water. A male sunfish will breed with more than one female, just as female sunfish will breed with more than one male. Average clutch size for the sunfish is around 2000 depending on the age of the female. Mature ova are around 1.1 mm in diameter. Reproductive maturity is reached the second year of life. They have been known to have a maximum lifespan of around seven years for primarily males. Currently, humans do not play a large role in influencing life history due to large populations and secluded areas.

Management

Currently, the redbreast sunfish is not on the federal or state endangered or threatened species list. The species is thriving in its natural habitat.

References

  • FishBase: Lepomis auritus
  • ITIS: Lepomis auritus
  • Ellis, Jack (1993). The Sunfishes-A Fly Fishing Journey of Discovery. Bennington, VT: Abenaki Publishers, Inc. ISBN 0-936644-17-6. 
  • Rice, F. Philip (1964). America's Favorite Fishing-A Complete Guide to Angling for Panfish. New York: Harper Row. 
  • Rice, F. Philip (1984). Panfishing. New York: Stackpole Books. ISBN 0-943822-25-4. 
  • Malo, John (1981). Fly-Fishing for Panfish. Minneapolis, Minnesota: Dillon Press Inc. ISBN 0-87518-208-9. 
  • Cooke, Steven, and David P. Philipp. Centrarchid Fishes: Diversity, Biology, and Conservation. Chichester, U.K.: Wiley-Blackwell, 2009. Print.
  • Dewoody, Andrew, Dean Fletcher, and David Wilkins. "Molecular Genetic Dissection of Spawning, Parentage, and Reproductive Tactics in a Population of Redbreast Sunfish, Lepomis Auritus." Evolution 52.6 (1998): 1802-810. Print.
  • Nadig, Susan G. Evaluating Potential Alteration of Genetic Diversity in Populations of Redbreast Sunfish (Lepomis Auritus) Using RAPD ASSAY. Thesis. The University of Tennessee Knoxville, 1996. Print.
  • Sharp, Stanley K. Serum Levels of 17B-Estradiol and Testosterone as Indicators of Environmental Stress in Redbreast Sunfish, Lepomis Auritus. Thesis. The University of Tennessee, Knoxville, 1994. Print.
  • Shepard, Kenneth L. Use of Standard Metabolic Rate as an Indicator of Environmental Stress in Redbreast Sunfish, Lepomis Auritus. Thesis. The University of Tennessee Knoxville, 1988. Print.