Agkistrodon piscivorus
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2008-07-17T03:48:21Z
TimVickers
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/* Feeding */ merge single sentence
{{taxobox
| name = ''Agkistrodon piscivorus''
| image = Agkistrodon piscivorus piscivorus CDC.png
| status = LC
| status_system = iucn3.1
| trend = stable
| regnum = [[Animal]]ia
| phylum = [[Chordate|Chordata]]
| subphylum = [[Vertebrate|Vertebrata]]
| classis = [[Reptile|Reptilia]]
| ordo = [[Squamata]]
| subordo = [[Serpentes]]
| familia = [[Viperidae]]
| subfamilia = [[Crotalinae]]
| genus = ''[[Agkistrodon]]''
| species = '''''A. piscivorus'''''
| binomial = ''Agkistrodon piscivorus''
| binomial_authority = ([[Bernard Germain de Lacépède|Lacépède]], 1789)
| synonyms = * ''Vipera aquatica'' - Catesby, 1743
* ''Crot''[''alus'']. ''Piscivorus'' - Lacépède, 1789
* ''C''[''rotalus'']. ''Aquaticus'' - Bonnaterre, 1790
* ''Scytale piscivora'' - Sonnini & Latreille, 1801
* ''Coluber Aquaticus'' - Shaw, 1802
* ''Coluber Tisiphone'' - Shaw, 1802
* ''Scytale piscivorus'' - Daudin, 1803
* [''Coluber'' (''Natrix'')] ''piscivorus'' - Merrem, 1820
* ''Colub''[''er'']. tisiphone'' - Cuvier, 1829
* ''Scytale piscivorus'' - Harlan, 1835
* ''Trigonocephalus piscivorus'' - Holbrook, 1838
* ''Cenchris piscivorus'' - Gray, 1842
* ''Toxicophis piscivorus'' - Baird & Girard, 1853
* ''Toxicophis pugnax'' - Baird & Girard, 1853
* ''Trigonocephalus tisiphone'' - Duméril, Bibron & Duméril, 1854
* ''A''[''ncistrodon'']. ''piscivorus'' - Cope, 1860
* ''A''[''ncistrodon'']. ''pugnax'' - Cope, 1860
* ''T''[''rigonocephalus'']. ''piscivorus'' var. ''pugnax'' - Jan, 1863
* ''Vipera Cench''[''ris'']. ''Piscivorus'' - Higgins, 1873
* ''Ancistrodon piscivorus'' Lacépède, ssp. ''piscivorus'' - Cope, 1875
* ''Ancistrodon piscivorus'' Lacépède, ssp. ''pugnax'' - Cope, 1875
* ''Ancistrodon piscivorus piscivorus'' - Yarrow, 1882
* ''Ancistrodon piscivorus pugnax'' - Yarrow, 1882
* [''Ancistrodon piscivorus''] Var. ''pugnax'' - Garman, 1884
* ''Agkistrodon piscivorus'' - Garman, 1890
* ''Ancistrodon piscivorus'' - Boulenger, 1896
* ''Agkistrodon piscivorus piscivorus'' - Gloyd & Conant, 1943
* ''Ancistrodon piscivorus piscivorus'' - Schmidt, 1953
* ''Agkistrodon piscivorus laurae'' - Stewart, 1974
* ''Agkistrodon piscivorus'' - Gloyd & Conant, 1990<ref name="McD99">McDiarmid RW, Campbell JA, Touré T. 1999. Snake Species of the World: A Taxonomic and Geographic Reference, vol. 1. Herpetologists' League. 511 pp. ISBN 1-893777-00-6 (series). ISBN 1-893777-01-4 (volume).</ref>
}}
:'''''Common names:''' cottonmouth, water moccasin, black moccasin, black snake,<ref name="W&W57">Wright AH, Wright AA. 1957. Handbook of Snakes. Comstock Publishing Associates. (7th printing, 1985). 1105 pp. ISBN 0-8014-0463-0.</ref> [[#Common names|more]].''
'''''Agkistrodon piscivorus''''' is a [[venomous snake|venomous]] [[Crotalinae|pitviper]] [[species]] found in the eastern [[United States]]. Large and notorious, it is semiaquatic and usually found in or near water. When agitated it will often stand its ground and gape at an intruder, exposing the white lining of its mouth. It is capable of delivering a painful and potentially fatal bite, but its reputation for aggression is undeserved as it is only likely to bite when picked up.
Once described as omnicarnivorous, it has a highly varied diet that has even been reported to include [[carrion]]. The specific name is derived from the Latin words ''piscis'' and ''voro'', which mean "fish" and "to eat", in reference to its diet.<ref name="C&L04">Campbell JA, Lamar WW. 2004. The Venomous Reptiles of the Western Hemisphere. Comstock Publishing Associates, Ithaca and London. 870 pp. 1500 plates. ISBN 0-8014-4141-2.</ref> Three [[subspecies]] are currently recognized, including the nominate subspecies described here.<ref name="ITIS">{{ITIS|ID=174299|taxon=Agkistrodon piscivorus|year=2007|date=29 May}}</ref>
==Description==
[[Image:Cottonmouth image 001.jpg|thumb|left|240 px|''A. p. piscivorus'', light-colored adult.]] This is the largest species of the genus ''[[Agkistrodon]]''. Adults commonly exceed 80 cm (roughly 2 ft. 8 in.) in length, with males growing larger than females. Occasionally, individuals may exceed 180 cm (5.9 ft) in length, especially in the eastern part of the range.<ref name="C&L04"/> According to Gloyd and Conant (1990), the largest recorded specimen of ''A. p. piscivorus'' was 74 inches (1879 mm) in length (Conant, 1975), based on a specimen caught in the [[Great Dismal Swamp|Dismal Swamp]] region and given to the Philadelphia Zoological Garden. It should be noted, however, that this snake had apparently been injured during capture, died several days later and was measured when straight and relaxed.<ref name="G&C90">Gloyd HK, Conant R. 1990. Snakes of the ''Agkistrodon'' Complex: A Monographic Review. Society for the Study of Amphibians and Reptiles. 614 pp. 52 plates. LCCN 89-50342. ISBN 0-916984-20-6.</ref>
The broad head is distinct from the neck, the snout blunt in profile with the rim of the top of the head extending forwards slightly further than the mouth.<ref name="G&C90"/> The body has a heavy build and a tail that is moderately long and slender. On top of the head, a generalized pattern of nine symmetrical head plates is present, although the [[parietal scales|parietal plates]] are often fragmented, especially towards the rear. A [[loreal scale]] is absent. There are 6-9 [[supralabials]] and 8-12 [[infralabials]]. At midbody, there are 23-27 rows of [[dorsal scales]].<ref name="C&L04"/> All dorsal scale rows have [[Keeled scales|keels]], although those on the lowermost scale rows are weak.<ref name="G&C90"/> In males/females, the [[ventral scales]] number 130-145/128-144 and the [[subcaudals]] 38-54/36-50. Many of the latter may be divided.<ref name="C&L04"/>
[[Image:Tiki3 cropped.JPG|thumb|left|''A. piscivorus'', neonate. Note the yellow tail tip.]] The color pattern consists of a brown, gray, tan, yellowish olive or blackish ground color, which is overlaid with a series of 10-17 crossbands that are dark brown to almost black. These crossbands, which usually have black edges, are sometimes broken along the dorsal midline to form a series of staggered half bands on either side of the body. These crossbands are visibly lighter in the center, almost matching the ground color, often contain irregular dark markings, and extend well down onto the ventral scales. The dorsal banding pattern fades with age, so that older individuals are an almost uniform olive brown, grayish brown or black. The belly is white, yellowish white or tan, marked with dark spots, and becomes darker posteriorly. The amount of dark pigment on the belly varies from virtually nothing to almost completely black. The head is a more or less uniform brown color, especially in ''A. p. piscivorus''. Subadult specimens may exhibit the same kind of dark, parietal spots that are characteristic of ''[[Agkistrodon contortrix|A. contortrix]]'', but sometimes these are still visible in adults. Eastern populations have broad dark postocular stripe, bordered with pale pigment above and below, that is faint or absent in western populations. The underside of the head is generally whitish, cream or tan.<ref name="C&L04"/>
Juvenile and subadult specimens generally have a more contrasting color pattern, with dark crossbands on a lighter ground color. The ground color is then tan, brown or reddish brown. The tip of the tail is usually yellowish, becoming greenish yellow or greenish in subadults, and then black in adults. On some juveniles, the banding pattern can also be seen on the tail.<ref name="C&L04"/>
This species is often confused with the copperhead, ''[[Agkistrodon contortrix|A. contortrix]]''. This is especially true for juveniles, but there are differences. ''A. piscivorus'' has broad dark stripes on the sides of its head that extend back from the eye, whereas ''A. contortrix'' has only a thin dark line that divides the pale supralabials from the somewhat darker color of the head.<ref name="C&L04"/>
The watersnakes of the genus ''[[Nerodia]]'' are also similar in appearance, being thick-bodied with large heads, but they have round pupils, no loreal pit, a single [[anal plate]], subcaudal scales that are divided throughout and a distinctive overall color pattern.<ref name="C&L04"/>
==Common names==
Water moccasin, cottonmouth, black moccasin, black snake, blunt-tail moccasin, congo, copperhead, cottonmouth water moccasin, cotton-mouthed snake, gapper, highland moccasin, lowland moccasin, mangrove rattler, moccasin, North American cottonmouth snake, North American water moccasin, North American water viper, pilot, rusty moccasin, saltwater rattler, rattler, stub-tail, stump moccasin, stump-tail moccasin, stump-tail viper, swamp lion, Texas moccasin, trap jaw, Troost's moccasin, true horn snake, true water moccasin, viper, water mokeson, water pilot, water rattlesnake, water viper,<ref name="W&W57"/> cotton-mouth snake,<ref name="Dit33">Ditmars RL. 1933. Reptiles of the World. Revised Edition. The MacMillan Company. 329 pp. 89 plates.</ref> gaper, snap jaw.<ref name="Meh87">Mehrtens JM. 1987. Living Snakes of the World in Color. New York: Sterling Publishers. 480 pp. ISBN 0-8069-6460-X.</ref>
[[Mark Catesby|Catesby]] (1743) referred to it as the "water viper", while [[Bernard Germain de Lacépède|Lacépède]] (1789) called it "le piscivore." The first appearance of "water moccasin" and "cotton mouth" was in [[John Edwards Holbrook|Holbrook's]] ''North American Herpetology'' (1838, 1842).<ref name="G&C90"/>
==Geographic range==
[[Image:Agkistrodon-piscivorus--range-map.png|thumb|left|240 px|Distribution. Blue = ''A. p. piscivorus''; Red = ''A. p. conanti'', Green = ''A. p. leucostoma'', Gray = integradation.<ref name="C&L04"/>]] Found in the eastern [[United States]] from [[Virginia]], south through the [[Florida]] peninsula and west to [[Arkansas]], southeastern [[Kansas]], eastern and southern [[Oklahoma]], and eastern and central [[Texas]]. A few records exist of the species being found along the [[Rio Grande]] in Texas, but these are thought to represent disjunct populations, now possibly extirpated. The [[Type locality (biology)|type locality]] given is "Carolina," although Schmidt (1953) proposed that this be restricted to the area around [[Charleston, South Carolina]].<ref name="McD99"/>
Campbell and Lamar (2004) mentions this species as being found in [[Alabama]], Arkansas, Florida, [[Georgia (U.S. state)|Georgia]], [[Illinois]], [[Indiana]], [[Kentucky]], [[Louisiana]], [[Mississippi]], [[Missouri]], [[North Carolina]], Oklahoma, [[South Carolina]], [[Texas]], and [[Virginia]].<ref name="C&L04"/> Maps provided by Campbell and Lamar (2004) and Wright and Wright (1957) also indicate its presence in eastern [[Tennessee]], extreme southeastern [[Nebraska]] and limit it to the western part of Kentucky.<ref name="C&L04"/><ref name="W&W57"/>
In Georgia it is found in the southern half of the state up to a few kilometers north of the [[fall line]] with few exceptions. Its range also includes the [[Ohio River Valley]] as far north as southern Illinois, and it inhabits many [[barrier island]]s off the coasts of the states where it is found.<ref name="C&L04"/>
==Conservation status==
This species is classified as Least Concern (LC) on the [[World Conservation Union|IUCN]] [[IUCN Red List|Red List of Threatened Species]] (v3.1, 2001).<ref name="ICUN">{{Redlist species|no=64298|genus=Agkistrodon|species=piscivorus|date=13 September|year=2007}}</ref> Species are listed as such due to their wide distribution, presumed large population, or because it is unlikely to be declining fast enough to qualify for listing in a more threatened category. The population trend is stable. Year assessed: 2007.<ref name="ICUN-31">{{Redlist CC2001|date=13 September|year=2007}}</ref>
Constant persecution and drainage of wetlands prior to development have taken a heavy toll on local populations. Despite this, however, it remains a common species in many areas.<ref name="Meh87">Mehrtens JM. 1987. Living Snakes of the World in Color. New York: Sterling Publishers. 480 pp. ISBN 0-8069-6460-X.</ref><ref name="G&C90"/>
==Habitat==
[[Image:Big cypress.jpg|thumb|right|240px|A cypress swamp in [[Big Cypress National Preserve]], south [[Florida]].]] This is the most aquatic species of the genus ''[[Agkistrodon]]'' and is usually associated with bodies of water, such as creeks, streams, marshes, swamps and the shores of ponds and lakes.<ref name="C&L04"/> The U.S. Navy (1991) describes it as inhabiting swamps, shallow lakes and sluggish streams, but that it is usually not found in swift, deep, cool water.<ref name="USN91">U.S. Navy. 1991. Poisonous Snakes of the World. US Govt. New York: Dover Publications Inc. 203 pp. ISBN 0-486-26629-X.</ref> Behler and King (1979) list its habitats as including lowland swamps, lakes, rivers, bayheads, sloughs, irrigation ditches, canals, rice fields and small clear rocky mountain streams.<ref name="B&K79">Behler JL, King FW. 1979. The Audubon Society Field Guide to North American Reptiles and Amphibians. New York: Alfred A. Knopf. 743 pp. LCCCN 79-2217. ISBN 0-394-50824-6.</ref>
It is also found in brackish water habitats and is sometimes seen swimming in salt water. It has been much more successful at colonizing Atlantic and Gulf coast [[barrier island]]s than the copperhead, ''[[Agkistrodon contortrix|A. contortrix]]''. However, even on these islands it tends to favor freshwater marshes. A study by Dunson and Freda (1985) describes it as not being particularly salt tolerant.<ref name="C&L04"/>
The snake is not limited to aquatic habitats, however, as Gloyd and Conant (1990) mention that large specimens have been found more than a mile (1.6 km) from water.<ref name="G&C90"/> In various locations the species is well adapted to less moist environments, such as [[Serenoa|palmetto]] thickets, pine-palmetto forest, pine woods in eastern [[Texas]], pine flatwoods in [[Florida]], eastern deciduous dune forest, dune and beach areas, [[Riparian zone|riparian]] forest and prairies.<ref name="C&L04"/>
==Behavior==
[[Image:Cottonmouth Snake, Gaping.jpg|thumb|left|220px|''A. p. piscivorus''. Gaping is part of the typical threat display.]] The aggressiveness of these snakes has been greatly exaggerated. In tests designed to measure the various behavioral responses by wild specimens to encounters with people, 23 of 45 (51%) tried to escape while 28 of 36 (78%) resorted to threat displays and other defensive tactics. Only when they were picked up with a mechanical hand were they likely to bite.<ref name="UGA">Whitfield Gibbons J, Dorcas ME. 2002. Defensive Behavior of Cottonmouths (''Agkistrodon piscivorus'') toward Humans. SREL Reprint #2583. [http://www.uga.edu/srel/Reprint/2583.htm Summary] at the [http://www.uga.edu/srel/ Savannah River Ecology Laboratory] at the [http://www.uga.edu/ University of Georgia]. Accessed [[May 29]] [[2007]].</ref>
When sufficiently stressed, this species engages in a characteristic threat display that includes vibrating its tail and throwing its head back with its mouth open to display the startling white interior,<ref name="Meh87">Mehrtens JM. 1987. Living Snakes of the World in Color. New York: Sterling Publishers. 480 pp. ISBN 0-8069-6460-X.</ref> while the neck and front part of the body are pulled into an S-shape.<ref name="C&G-G&C90">Carpenter CC, Gillingham JC. Ritualized Behavior in ''Agkistrodon'' and Allied Genera. 523-531. ''In'' Gloyd HK, Conant R. 1990. Snakes of the ''Agkistrodon'' Complex: A Monographic Review. Society for the Study of Amphibians and Reptiles. 614 pp. 52 plates. LCCN 89-50342. ISBN 0-916984-20-6.</ref> Many of its common names, including ''"Cottonmouth"'' and ''"gapper"'', refer to this behavior, while its habit of snapping its jaws shut when anything touches its mouth has earned it the name ''"trap-jaw"'' in some areas.<ref name="C&B42">Conant R, Bridges W. 1942. What Snake is That? A Field Guide to the Snakes of the United States East of the Rocky Mountains. D. Appleton-Century Company Inc. 163 pp. 32 plates.</ref> Other defensive responses can include flattening the body<ref name="C&G-G&C90"/> and emitting a strong, pungent secretion from the anal glands located at the base of the tail.<ref name="C&L04"/> This musk may be ejected in thin jets if the snake is sufficiently agitated or restrained. The smell has been likened to that of a [[Goat|billy goat]], as well as to a genus of common floodplane weeds, ''[[Pluchea]]'', that also have a penetrating odor.<ref name="G&C90"/>
[[Image:Agkistrodonpconanti1.jpg|thumb|right|220px|''[[Agkistrodon piscivorus conanti|A. p. conanti]]'', swimming. Unlike non-venomous species, much of its body floats above the surface.]]Harmless watersnakes of the genus ''[[Nerodia]]'' are often mistaken for it. These are also semiaquatic, thick-bodied snakes with large heads that can be aggressive when provoked,<ref name="C&L04"/> but they behave differently. For example, watersnakes usually flee quickly into the water, while ''A. piscivorus'' often stands its ground with its threat display. In addition, watersnakes do not vibrate their tails when excited.<ref name="Con75">Conant R. 1975. A Field Guide to Reptiles and Amphibians of Eastern and Central North America. Second Edition. First published in 1958. Houghton Mifflin Company Boston. 429 pp. 48 plates. ISBN 0-395-19979-4. ISBN 0-395-19979-8 (pbk.).</ref> ''A. piscivorus'' usually holds its head at an angle of about 45° when swimming or crawling.<ref name="C&L04"/> It swims with much of its body floating above the surface, while watersnakes tend to swim mostly below the surface, sometimes with their heads protruding.
Brown (1973) considered their heavy muscular bodies to be a striking characteristic, stating that this made it difficult to hold them for venom extraction due to their strength.<ref name="Bro73">Brown JH. 1973. Toxicology and Pharmacology of Venoms from Poisonous Snakes. Springfield, Illinois: Charles C. Thomas. 184 pp. LCCCN 73-229. ISBN 0-398-02808-7.</ref>
This species may be active during the day as well as at night. However, on bright, sunny days they are usually found coiled or stretched out somewhere in the shade. In the morning and on cool days they can often be seen basking in the sunlight. At night, however, they are at their most active, when they are usually found swimming or crawling.<ref name="C&L04"/> Contrary to popular belief, they are capable of biting while underwater.<ref name="Meh87"/>
In the north, they hibernate during the winter months. Niell (1947, 1948) made observations in [[Georgia (U.S. state)|Georgia]] and noted that they were one of the last species to seek shelter, often being found active until the first heavy frosts. At this point they moved to higher ground and could be found in rotting pine stumps by tearing away the bark. These snakes could be quite active upon discovery and would then attempt burrow more deeply into the soft wood or escape to the nearest water. In southeastern [[Virginia]], Wood (1954) reported seeing migratory behavior in late October and early November. During a period of three or four days, as many as 50 individuals could be seen swimming across [[Back Bay National Wildlife Refuge|Back Bay]] from the bayside swamps of the [[barrier island]]s to the mainland. He suggested that this might have something to do with hibernating habits. In the southern parts of its range, hibernation may be short or omitted altogether.<ref name="G&C90"/>
==Feeding==
[[Raymond Ditmars|Ditmars]] (1912) described this species as ''omnicarnivorous''. Its diet includes mammals, birds, amphibians, fish, snakes, small turtles and small alligators. Cannibalism has also been reported. Normally, though, the bulk of its diet consists of fish and frogs. On occasion, juvenile specimens feed on invertebrates.<ref name="G&C90"/> [[Catfish]] are often eaten, although the sharp spines sometimes cause injuries. Toads of the genus ''[[Bufo]]'' are apparently avoided.<ref name="C&L04"/>
Many authors have described the prey items taken under natural circumstances. Although fish and frogs are their most common prey, they will eat almost any small vertebrate. Campbell and Lamar (2004) provide an exhaustive list of species that have reportedly been preyed upon by ''A. piscivorus'', including cicadas, caterpillars, land snails (''[[Euglandina rosea]]''), catfish (''[[Ictalurus furcatus]]''), pike (''[[Esox|Esox ssp.]]''), sunfishes (''[[Lepomis|Lepomis ssp.]]''), bass (''[[Micropterus|Micropterus ssp.]]''), sirens (''[[Siren (genus)|Siren sp.]]''), eastern newts (''[[Notophthalmus viridescens]]''), brook salamanders (''[[Eurycea|Eurycea sp.]]''), Ouachita dusky salamanders (''[[Desmognathus brimleyorum]]''), spadefoot toads (''[[Scaphiopus|Scaphiopus]]''), eastern narrowmouth toads (''[[Gastrophryne carolinensis]]''), northern cricket frogs (''[[Acris crepitans]]''), West Indian treefrogs (''[[Osteopilus septentrionalis]]''), treefrogs (''[[Hyla|Hyla sp.]]''), true frogs (''[[Rana (genus)|Rana sp.]]''), green anoles (''[[Anolis carolinensis]]''), skinks (''[[Eumeces|Eumeces sp.]]''), eastern glass lizards (''[[Ophisaurus ventralis]]''), ground skinks (''[[Scincella lateralis]]''), mudsnakes (''[[Farancia abacura]]''), hog-nosed snakes (''[[Heterodon platirhinos]]''), kingsnakes (''[[Lampropeltis|Lampropeltis sp.]]''), watersnakes (''[[Nerodia|Nerodia sp.]]''), crayfish snakes (''[[Regina (genus)|Regina sp.]]''), brown snakes (''[[Storeria dekayi]]''), gartersnakes and ribbonsnakes (''[[Thamnophis|Thamnophis sp.]]''), other cottonmouths (''A. piscivorus''), rattlesnakes (''[[Crotalus|Crotalus sp.]]''), common snapping turtles (''[[Chelydra serpentina]]''), mud turtles (''[[Kinosternon|Kinosternon sp.]]''), common musk turtles (''[[Sternotherus odoratus]]''), Florida cooters (''[[Pseudemys floridana]]''), sliders (''[[Trachemys scripta]]''), eastern box turtles (''[[Terrapene carolina]]''), Florida softshell turtles (''[[Apalone ferox]]''), baby American alligators (''[[Alligator mississippiensis]]''), wood thrushes (''[[Hylocichla mustelina]]''), chickadees (''[[Parus|Parus sp.]]''), cardinals (''[[Cardinalis cardinalis]]''), unidentified [[passerine]]s, small ducks, juvenile anhingas (''[[Anhinga anhinga]]''), common egrets (''[[Ardea alba]]''), egrets, glossy ibises and their eggs (''[[Plegadis falcinellus]]''), tricolor herons (''[[Egretta tricolor]]''), herons and their eggs, pied-billed grebes (''[[Podilymbus podiceps]]''), short-tailed shrews (''[[Blarina brevicauda]]''), least shrews (''[[Cryptotis parva]]''), southeastern shrews (''[[Sorex longirostris]]''), eastern moles (''[[Scalopus aquaticus]]''), muskrats (''[[Ondatra zibethicus]]''), rice rats (''[[Oryzomys palustris]]''), hispid pocket mice (''[[Perognathus hispidus]]''), black rats (''[[Rattus rattus]]''), squirrels (''[[Sciurus|Sciurus sp.]]''), rabbits (''[[Sylvilagus|Sylvilagus sp.]]'') and bats.<ref name="C&L04"/>
Fish are captured by cornering them in shallow water, usually against the bank or under logs. They take advantage when bodies of water begin to dry up in the summer or early fall and gorge themselves on the resulting high concentrations of fish and tadpoles. A study by Savitsky (1992) found that they were surprisingly unsuccessful at seizing either live or dead fish underwater.<ref name="C&L04"/>
They are opportunistic feeders and will sometimes eat [[carrion]]. Campbell and Lamar (2004) describe having seen them feeding on fish heads and viscera that had been thrown into the water from a dock. Heinrich and Studenroth (1996) report an occasion in which an individual was seen feeding on the butchered remains of a wild hog (''[[Sus scrofa]]'') that had been thrown into Cypress Creek.<ref name="C&L04"/>
Conant (1929) gives a detailed account of the feeding behavior of a captive specimen from [[South Carolina]]. When prey was introduced, the snake quickly became attentive and made an attack. Frogs and small birds were seized and held until movement stopped. Larger prey was approached in a more cautious manner; a rapid strike was executed after which the snake would withdraw. In 2.5 years the snake had accepted three species of frogs, including a large [[bullfrog]], a spotted salamander, water snakes, garter snakes, sparrows, young rats and three species of mice.<ref name="G&C90"/> Brimley (1944) described a captive specimen that ate copperheads (''[[Agkistrodon contortrix]]''), as well as members of its own species, keeping its fangs embedded in its victims until they had been immobilized.<ref name="G&C90"/>
Young individuals have yellowish or greening tail tips and engage in caudal luring. The tail tip is wriggled to lure prey, such as frogs and lizards, within striking distance. Wharton (1960) observed captive specimens exhibiting this behavior between 07:20 and 19:40 hours, which suggests that it is a daytime activity.<ref name="C&L04"/>
==Predators==
In turn these snakes are preyed upon by snapping turtles (''[[Chelydra serpentina]]''), American alligators (''[[Alligator mississippiensis]]''), bullfrogs (''[[Rana catesbeiana]]''), horned owls (''[[Bubo virginianus]]''), eagles, loggerhead shrikes (''[[Lanius ludovicianus]]''), and large wading birds, such as [[heron]]s, [[Crane (bird)|cranes]] and [[egret]]s.<ref name="G&C90"/><ref name="C&L04"/>
They are also preyed upon by [[Ophiophagy|ophiophagous]] snakes, including their own species (cannibalism). Humphreys (1881) described how a 34-inch (864 mm) specimen that was killed and eaten by a 42-inch (1067 mm) captive kingsnake. On the other hand, Neill (1947) reported that captive kingsnakes (''[[Lampropeltis getula]]'') were loathe to attack them, being successfully repelled with "body blows."<ref name="G&C90"/> Also called body-bridging, this is a specific defensive behavior against ophiophagous snakes, first observed in certain rattlesnake (''[[Crotalus]]'') species by [[Laurence Monroe Klauber|Klauber]] (1927), that involves raising a section of the middle of the body above the ground to varying heights. This raised loop may then be held in this position for varying amounts of time, shifted in position, or moved towards the attacker. In the latter case, it is often flipped or thrown vigorously in the direction of the assailant. In ''A. piscivorus'', the loop is raised laterally, with the belly facing towards the attacker.<ref name="C&G-G&C90"/>
==Reproduction==
This species is [[Ovoviviparity|ovoviviparous]], with females giving birth to 1-16 live young and possibly as many as 20. However, litters of 6-8 are the most common. Neonates are 222-350 mm in length (excluding runts), with the largest being ''[[Agkistrodon piscivorus conanti|A. c. conanti]]'' and ''[[Agkistrodon piscivorus leucostoma|A. c. leucostoma]]'' the smallest. If weather conditions are favorable and food is readily available, growth is rapid and females may reproduce at less than three years of age and a total length of as little as 600 mm. The young are born in August or September, while mating may occur during any of the warmer months of the year, at least in certain parts of its range.<ref name="G&C90"/>
Regarding ''A. p. piscivorus'', an early account by [[Leonhard Hess Stejneger|Stejneger]] (1895) describes a pair in the [[Berlin Zoological Garden]] that mated on January 21, 1873, after which eight neonates were discovered in the cage on July 16 of that year. The young were each 260 mm in length and 15 mm thick. They shed for the first time within two weeks, after which they accepted small frogs, but not fish.<ref name="G&C90"/>
Combat behavior between males has been reported on a number of occasions and is very similar in form to that seen in many other viperid species. An important factor in sexual selection, it allows for the establishment and recognition of dominance as males compete for access to sexually active females.<ref name="C&G-G&C90"/>
A few accounts exist that describe females defending their newly born litters. Wharten (1960, 1966) reported several cases where females found near their young stood their ground and considered these to be examples of guarding behavior. Another case was described by Walters and Card (1996) in which a female was found at the entrance of a chamber with seven neonates crawling on or around her. When one of the young was moved a short distance from the chamber, she seemed to be agitated and faced the intruder. Eventually, all of her offspring retreated into the chamber, but the female remained at the entrance, ready to strike.<ref name="C&L04"/>
==Venom==
Bites from this species are relatively frequent in the lower [[Mississippi embayment|Mississippi River Valley]] and along the coast of the [[Gulf of Mexico]], although fatalities are rare.<ref name="USN91"/> Allen and Swindell (1948) compiled a record of ''A. piscivorus'' bites in the state of [[Florida]] from newspaper accounts and data from the Bureau of Vital Statistics: 1934, 8 bites and 3 fatalities (no further fatalities were recorded after this year); 1935, 10; 1936, 16; 1937, 7; 1938, 6; 1939, 5; 1940, 3; 1941, 6; 1942, 3; 1943, 1; 1944, 3. Wright and Wright (1957) report having encountered these snakes on countless occasions, often almost stepping on them, but never being bitten. In addition, they heard of no reports of any bites among 400 cypress cutters in the [[Okefenokee Swamp]] during the entire summer of 1921. These accounts indicate that the species is not particularly aggressive.<ref name="W&W57"/>
Brown (1973) gives an average venom yield (dried) of 125 mg, with a range of 80-237 mg, along with [[LD50|LD<font size ="-1"><sub>50</sub></font>]] values of 4.0, 2.2, 2.7, 3.5, 2.0 mg/kg [[Intravenous therapy|IV]], 4.8, 5.1, 4.0, 5.5, 3.8, 6.8 mg/kg [[Peritoneum#Intraperitoneal|IP]] and 25.8 mg/kg [[Subcutis|SC]] for toxicity.<ref name="Bro73"/> Wolff and Githens (1939) describe a 60-inch (152 cm) specimen that yielded 3.5 cc of venom during the first extraction and 4.0 cc five weeks later (1.094 grams of dried venom).<ref name="W&W57"/>
Symptoms commonly include [[ecchymosis]] and swelling. The pain is generally more severe than bites from the copperhead (''[[Agkistrodon contortrix|A. contortrix]]''), but less so than those from rattlesnakes (''[[Crotalus|Crotalus sp.]]''). The formation of [[vesicles]] and [[Blister|bullae]] is less common than with rattlesnake bites, although [[necrosis]] can occur. [[Myokymia]] is sometimes reported.<ref name="Nor-C&L04">Norris R. 2004. Venom Poisoning in North American Reptiles. ''In'' Campbell JA, Lamar WW. 2004. The Venomous Reptiles of the Western Hemisphere. Comstock Publishing Associates, Ithaca and London. 870 pp. 1500 plates. ISBN 0-8014-4141-2.</ref> On the other hand, the U.S. Navy (1991) states that the venom has strong [[Proteolysis|proteolytic]] activity that can lead to severe tissue destruction.<ref name="USN91"/>
[[CroFab|CroFab polyvalent antivenin]] is used to treat bites from this species.<ref name="MAV">[http://www.toxinfo.org/antivenoms/indication/AGKISTRODON_PISCIVORUS.html ''Agkistrodon piscivorus''] at [http://www.toxinfo.org/antivenoms/ Munich AntiVenom INdex (MAVIN)]. Accessed [[18 June]] [[2008]].</ref>
==Subspecies==
{|cellspacing=0 cellpadding=2 border=1 style="border-collapse: collapse;"
!bgcolor="#f0f0f0"|Subspecies<ref name="ITIS"/>
!bgcolor="#f0f0f0"|Authority<ref name="ITIS"/>
!bgcolor="#f0f0f0"|Common name<ref name="G&C90">Gloyd HK, Conant R. 1990. Snakes of the Agkistrodon Complex: A Monographic Review. Society for the Study of Amphibians and Reptiles. 614 pp. 52 plates. LCCN 89-50342. ISBN 0-916984-20-6.</ref>
!bgcolor="#f0f0f0"|Geographic range<ref name="G&C90"/>
|-
|''[[Agkistrodon piscivorus conanti|A. p. conanti]]''
|[[Howard Gloyd|Gloyd]], 1969
|Florida cottonmouth
|style="width:40%"|The [[United States]], in extreme southern [[Georgia (U.S. state)|Georgia]] and virtually all of the state of [[Florida]], including many of the islands off the coast.
|-
|''[[Agkistrodon piscivorus leucostoma|A. p. leucostoma]]''
|([[G. Troost|Troost]], 1836)
|Western cottonmouth
|The United States, from southern [[Alabama]] along coast of the [[Gulf of Mexico]], including many offshore islands, to southeastern and central [[Texas]], and north to [[Oklahoma]], [[Missouri]], [[Illinois]] and [[Indiana]].
|-
|''A. p. piscivorus''
|([[Bernard Germain de Lacépède|Lacépède]], 1789)
|Eastern cottonmouth
|The United States in southeastern [[Virginia]], the Atlantic Coastal Plain and lower Piedmont of [[North Carolina|North]] and [[South Carolina]], including the banks, peninsulas and islands along the Atlantic coast, and west across Georgia.
|-
|}
==See also==
* [[List of crotaline species and subspecies]]
* {{c|Crotalinae by common name}}
* {{c|Crotalinae by taxonomic synonyms}}
* [[Snakebite]]
==References==
{{reflist}}
==External links==
{{Commons|Agkistrodon piscivorus}}
* {{NRDB species|genus=Agkistrodon|species=piscivorus|date=7 December|year=2007}}
* [http://www.rlephoto.com/herps/cottonmouth/index.htm Cottonmouth close up photos] at [http://www.rlephoto.com/ rlephoto.com]. Accessed [[7 December]] [[2007]].
* [http://nationalzoo.si.edu/Animals/ReptilesAmphibians/Facts/FactSheets/Cottonmouth.cfm Cottonmouth Fact Sheet] at [http://nationalzoo.si.edu/ Smithsonian National Zoological Park]. Accessed [[7 December]] [[2007]].
* {{YouTube|cZSuPPd6f3M|Video of ''Agkistrodon piscivorus''}}. Accessed [[3 July]] [[2008]].
[[Category:Crotalinae]]
[[Category:Reptiles of the United States]]
[[Category:Fauna of the Southeastern United States]]
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