The timber rattlesnake (Crotalus horridus), also known commonly as the banded rattlesnake, and the canebrake rattlesnake in the southern United States,Wright AH, Wright AA (1957). Handbook of Snakes of the United States and Canada. Ithaca and London: Comstock Publishing Associates, a division of Cornell University Press. (7th printing, 1985). 1,105 pp. (in two volumes). . (Crotalus horridus, pp. 956–966.) is a species of pit viper in the family Viperidae. The species is native to the eastern United States. Like all other pit vipers, it is venomous, with a very toxic bite. Its venom is extremely potent, and both hemorrhagic and neurotoxic venom are present depending on population and location.Rokyta, D. R., Wray, K. P., McGivern, J. J., & Margres, M. J. (2015). The transcriptomic and proteomic basis for the evolution of a novel venom phenotype within the Timber Rattlesnake (Crotalus horridus). Toxicon, 98, 34-48. C. horridus is the only rattlesnake species in most of the populous Northeastern United States and is one of the most northerly distributed venomous snakes in North America.Conant R (1975). A Field Guide to Reptiles and Amphibians of Eastern and Central North America, Second Edition. (First published in 1958). Boston: Houghton Mifflin Company. xviii + 429 pp. + Plates 1–48. (hardcover), (paperback). (Crotalus horridus, pp. 233–235 + Plate 35 + Map 178.)Brown, William S. (1991). "Female Reproductive Ecology in a Northern Population of the Timber Rattlesnake, Crotalus horridus ". Herpetologica 47 (1): 101-115. There are no subspecies that are recognized as being valid.
Taxonomy The timber rattlesnake was one of the many reptile species originally described by Carl Linnaeus in the landmark 1758 10th edition of his Systema Naturae, and still bears its original name Crotalus horridus.
The subspecies C. h. atricaudatus (Latreille in Sonnini and Latreille, 1802), often referred to as the canebrake rattlesnake, is currently considered invalid. Previously, it was recognized by Gloyd (1936) and Klauber (1936). Based on an analysis of geographic variation, Pisani et al. (1972) concluded no subspecies should be recognized. This was rejected by Conant (1975), but followed by Collins and Knight (1980). Brown and Ernst (1986) found evidence for retaining the two subspecies, but stating them apart without having more information than usual is not possible, including adult size, color pattern, the number of dorsal scale rows, and the number of ventral scales. Dundee and Rossman (1989) recognized C. h. atricaudatus, but others take a more neutral point of view.
The timber rattlesnake is one of 36 species in the genus Crotalus. This genus can be distinguished from Sistrurus by the small scales atop the head, rather than nine large scales found on Sistrurus.
Etymology The name Crotalus is Latin for a rattleErnst, Carl H. and Evelyn M. Ernst. 2003. Snakes of the United States and Canada. Smithsonian Books. Washington D.C. xi, 668 pp. (see pages 563-564) or, crŏtălisso to rattle or the sound of the castanet.Lewis, Charlton T. 1993. A Latin Dictionary, founded on Andrews' edition of Freund's Latin Dictionary, revised, enlarged, and in great part rewritten. Oxford University Press. Oxford. xiv, 2019 pp. (see page 484) Horridus is Latin, meaning horrid or dreadful, presumably in reference to its potentially lethal venom. Although southern populations are generally no longer recognized as a valid subspecies, the name canebrake rattlesnake (Crotalus horridus atricaudatus) is occasionally still used and commonly encountered in older literature. Atricaudatus is Latin meaning black-tailed ( = black, and = tailed).
Description Adults usually grow to total length of . In Pennsylvania, the smallest size females that could produce viable eggs was .Galligan, John H.; Dunson, William A. (1979). "Biology and status of timber rattlesnake (Crotalus horridus) populations in Pennsylvania". Biological Conservation 15 (1): 13–58. Most adult timber rattlesnakes found measure less than in total length and weigh between , often being towards the lower end of that range.Timber Rattlesnake (Crotalus horridus). Tpwd.state.tx.us. Retrieved on 2013-01-05.Fitch, Henry S.; Pisani, George R.; Greene, Harry W.; Echelle, Alice F.; Zerwekh Michael (2004). "A field study of the timber rattlesnake in Leavenworth County, Kansas". Journal of Kansas Herpetology 11: 18-24.Brown, William S.; Kéry, Marc; Hines, James E. Hines (2007). "Survival of timber rattlesnakes (Crotalus horridus) estimated by capture-recapture models in relation to age, sex, color morph, time, and birthplace". Copeia 2007 (3): 656-671.Clark, Rulon W. (2006). "Fixed Videography to Study Predation Behavior of an Ambush Foraging Snake, Crotalus horridus ". Copeia 2006 (2): 181–187. The maximum reported total length is (Klauber, 1956). Holt (1924) mentions a large specimen caught in Montgomery County, Alabama, which had a total length of and weighed . Large specimens can reportedly weigh as much as .ANIMAL BYTES – Canebrake Rattlesnake. Seaworld.org. Retrieved on 2013-01-05.
The dorsal scales are keeled (Crotalus horridus, pp. 688–689 + Plates 619, 620, 653.) and arranged in 21–26 scale rows at midbody (usually 25 rows in the southern part of its geographic range, and 23 rows in the northern part). The ventral scales number 158–177 in males and 163–183 in females. Males have 20–30 subcaudal scales, while females have 15–26. The rostral scale is normally a little taller than it is wide. In the internasal-prefrontal area there are 4–22 scales that include 2 large, triangular internasal scales that border the rostral, followed by two large, quadrangular prefrontal scales (anterior canthals) that may contact each other along the midline, or may be separated by many small scales. Between the supraocular and internasal scales, only a single canthal scale is present. Five to seven intersupraocular scales are seen. The number of prefoveal scales varies between two and eight. Usually, the first supralabial scale is in broad contact with the prenasal scale, although slightly to moderately separated along its posteroventral margin by the most anterior prefoveals.
Dorsally, they have a pattern of dark brown or black crossbands on a yellowish-brown or grayish background. The crossbands have irregular zig-zag edges, and may be V- or M-shaped. Often a rust-colored vertebral stripe is present. Ventrally, they are yellowish, uniform, or marked with black.Boulenger GA (1896). Catalogue of the Snakes in the British Museum (Natural History), Volume III., Containing the ... Viperidæ. London: Trustees of the British Museum (Natural History). (Taylor and Francis, printers). xiv + 727 pp. + Plates I–XXV. (Crotalus horridus, pp. 578–580). Melanism is common, and some individuals are very dark, almost solid black.Schmidt KP, Davis DD (1941). Field Book of Snakes of the United States and Canada. New York: G.P. Putnam's Sons. 365 pp. (Crotalus horridus horridus, pp. 301–302 + Plate 33; Crotalus horridus atricaudatus, p. 302). The tails of C. horridus are black and can be described as 'velvety.'
Distribution and habitat
Timber rattlesnakes are present in the eastern United States from southern Minnesota and southern New Hampshire, south to East Texas and North Florida.Conant R, Collins JT (1998). Reptiles and Amphibians of Eastern/Central North America. New York: Houghton Mifflin. One hundred and fifteen rattlesnakes have been marked within Brown County State Park in Indiana, one of the few places where they can be found in the state.
Its historic range includes southern Ontario and southern Quebec in Canada, but in May 2001, the Canadian Species at Risk Act listed it as extirpated in Canada.Crotalus horridus at Species at Risk Public Registry . Accessed 23 June 2008. A Canadian government sponsored recovery strategy is under study to support the reintroducing of this predator of many pests to its former Canadian habitat.
Many were present in some of the thick forest areas of central and southeastern Iowa, mostly within the Mississippi, Skunk, Iowa, and Des Moines River valleys, in several places in these areas; bites from timber rattlesnakes have been widespread, especially in a localized area of Geode State Park, in southeastern Henry County, along Credit Island Park, in southern Scott County, and in the forested areas of southern Clinton County. The museum at Amana Colony, Iowa, asserts that one founding family lost their firstborn, a daughter, at the age of three, due to a rattlesnake bite she received while playing on a woodpile in the 19th century.
In Pennsylvania, it is not present west of Chestnut Ridge, which is in the Laurel Highlands, nor is it present in the urban areas of the southeastern corner of the state. Thus, its range does not include Philadelphia and Pittsburgh, the two largest cities in Pennsylvania.
C. horridus is extirpated from Michigan, Delaware, Maine and Rhode Island, and is considered close to extirpation in New Hampshire.
Generally, this species is found in deciduous forests in rugged terrain. C. horridus can be found in a variety of terrestrial habitats including lowland cane thickets (thus the common name canebrake rattlesnake), high areas around swamps and river floodplains, hardwood and pine forests, mountainous areas, and rural habitats in farming areas. During the summer, gravid females seem to prefer open, rocky ledges where the temperatures are higher, while males and nongravid females tend to spend more time in cooler, denser woodland with more closed forest canopy.Timber Rattlesnake Fact Sheet at NY State Dept. of Environmental Conservation. Accessed 8 February 2007.
Behavior Female timber rattlers often bask in the sun before giving birth, in open rocky areas known as "basking knolls".
During the winter, timber rattlesnakes brumate in dens and limestone crevices, often together with copperheads (Agkistrodon contortrix) and rat snakes (Pantherophis alleghaniensis, P. obsoletus, and P. spiloides). Timber rattlesnakes exhibit high levels of philopatry to their natural hibernaculum, which means that they are likely to return to the same hibernaculum, or communal wintering den, each year. Timber rattlesnakes occupying the same hibernaculum (especially juveniles and pregnant females) have been reported to be more closely related to each other than to the rattlesnakes in neighboring dens; studies have suggested this behavior may be related to juveniles' ability to track chemical cues from relatives. Timber rattlesnakes have also been found to leave dens multiple times in midwinter to briefly bask.
Males often mate farther away from winter hibernacula than females.
Reproduction
A lifetime reproduction study of a population in the Adirondack Mountains of New York found that the first reproduction occurs at a mean age of 9.6 years. The mean length of reproductive cycles is 4.2 years, the mean reproductive life span is 9.6 years, and the average fecundity is 7.7 offspring per litter. Nonviable offspring were found in 20% of the field litters. Most females only reproduced once in a lifetime. Macrogeographic differences were observed within the population and may have correlated resource levels influencing growth rates and additionally human encounters could influence survival.
Diet