Crotalus horridus, commonly known as timber rattlesnake, canebrake rattlesnake or banded rattlesnake, is a species of venomous pit viper found in the eastern United States. This is the only rattlesnake species in most of the populous northeastern United States. No subspecies is currently recognized.
Adults usually grow to total length of 91–152 cm (35.8–59.8 in). The maximum reported total length is 189.2 cm (74.5 in) (Klauber, 1956). Holt (1924) mentions a large specimen caught in Montgomery County, Alabama, which had a total length of 159 cm (62.6 in) and weighed 2.5 kg (5.5 lb). Large specimens can reportedly weigh as much as 4.5 kg (9.9 lb). Most timber rattlesnakes found measure less than 100 cm (39 in) in total length and weigh 580–900 g (20–32 oz).
The dorsal scales are keeled 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 higher 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 2 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, only a single canthal scale is present. There are 5–7 intersupraocular scales. The number of prefoveal scales varies between 2 and 8. 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-shaped or M-shaped. Often a rust-colored vertebral stripe is present. Ventrally they are yellowish, uniform or marked with black. Melanism is common, and some individuals are very dark, almost solid black.
Geographic range 
Although several experts disagree, many were found 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.
In Pennsylvania, it is not found west of Chestnut Ridge, which is in the Laurel Highlands, nor is it found in the southeastern corner of the state. Thus, its range does not include the areas of Philadelphia and Pittsburgh, the two largest cities in Pennsylvania.
Generally, this species is found in deciduous forests in rugged terrain. During the summer, gravid (pregnant) 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.
Female timber rattlers often bask in the sun before giving birth, in open rocky areas known as "basking knolls".
Potentially, this is one of North America's most dangerous snakes, due to its long fangs, impressive size, and high venom yield. This is to some degree offset by its relatively mild disposition. Before striking, they often perform a good deal of preliminary rattling and feinting. Cist (1845) described how he lived in western Pennsylvania for many years, and the species was quite common there, but in all that time, he heard of only a single death resulting from its bite.
Considerable geographic and ontogenetic variation occurs regarding the toxicity of the venom, which can be said for many rattlesnake species. Four venom patterns have been described for this species: Type A is largely neurotoxic, and is found in various parts of the southern range. One effect of the toxin can be generalized myokymia. Type B is hemorrhagic and proteolytic, and is found consistently in the north and in parts of the southeast. Type A + B is found in areas where the aforementioned types apparently intergrade in southwestern Arkansas and northern Louisiana. Type C venom has none of the above components and is relatively weak.
The neurotoxic component of the type A venom is referred to as canebrake toxin, and is a phospholipase A2. It is analogous to the neurotoxins found in the venoms of several other rattlesnake species, and when present, contributes significantly to the overall toxicity. Other components found in the venom include a small basic peptide that works as a myotoxin, a fibrinogen-clotting enzyme that can produce defibrination syndrome, and a bradykinin-releasing enzyme.
The timber rattlesnake was designated the state reptile of West Virginia in 2008. That state's legislature praised "...a proud contribution by the eighth grade class at Romney Middle School, from West Virginia's oldest county, in West Virginia's oldest town, to have been instrumental in making the timber rattlesnake the state reptile..."
This snake became a prominent symbol during the American Revolution in part because it had a fearsome reputation. The use of the timber rattlesnake as a symbol of American anger and resolve to defend itself was no idle threat. During the period of 1763–1787, medical knowledge was not up to the challenge of treating a timber rattlesnake's bite. First, at the time, European standards of medical practice were based on the ideas and concepts of Galen, where disease was caused by imbalances in the body; this was the standard to which all doctors practicing medicine in the colonies were trained.[unreliable source?] Because of the then poorly understood effects on the nervous or hematological system of this species' venom, a physician would prescribe a course of action that wound up killing the patient faster (bleeding with leeches) or prescribing herbs without testing of their efficacy as a cure beyond imitation of Native American practices[unreliable source?] Secondly, Linnaeus only described and identified this snake in 1758; firsthand experience with timber rattlesnakes among London scientists would have been poor, the flora and fauna of the colonies would have been disdained as savage by thinking circles, and published information on its habits would have been thin, allowing for hearsay and superstition to grow on both sides of the Atlantic.
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 state it is not possible to tell them apart without having more information than usual, 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.
Conservation status 
This species is classified as least concern on the IUCN Red List (assessed in 2007). Species are listed as such due to their wide distribution, presumed large population, or because they are unlikely to be declining fast enough to qualify for listing in a more threatened category.
The timber rattlesnake is listed as endangered in New Jersey, Vermont, Massachusetts, New Hampshire, Indiana, and Ohio, and it is threatened in New York, Connecticut, Illinois, Minnesota, and Texas.
See also 
- List of crotaline species and subspecies
- Crotalus by common name
- Crotalus by taxonomic synonyms
- Crotalinae by common name
- Crotalinae by taxonomic synonyms
- Hammerson, G.A. (2007). Crotalus horridus. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2.
- McDiarmid RW, Campbell JA, Touré T. 1999. Snake Species of the World: A Taxonomic and Geographic Reference, Volume 1. Herpetologists' League. ISBN 1-893777-00-6 (series). ISBN 1-893777-01-4 (volume).
- Wright AH, Wright AA. 1957. Handbook of Snakes of the United States and Canada. Comstock Publishing Associates. Ithaca and London. (7th printing, 1985). ISBN 0-8014-0463-0. (Crotalus horridus, pp. 956–966.)
- 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. ISBN 0-395-19979-4. (Crotalus horridus, pp. 233–235 + Plate 35 + Map 178.)
- "Crotalus horridus". Integrated Taxonomic Information System. Retrieved 8 February 2007.
- Campbell JA & Lamar WW (2004). The Venomous Reptiles of the Western Hemisphere (2 volumes). Comstock Publishing Associates. ISBN 0-8014-4141-2.[page needed]
- ANIMAL BYTES – Canebrake Rattlesnake. Seaworld.org. Retrieved on 2013-01-05.
- Timber Rattlesnake (Crotalus horridus). Tpwd.state.tx.us. Retrieved on 2013-01-05.
- Behler JL & King FW (1979). The Audubon Society Field Guide to North American Reptiles and Amphibians. Alfred A. Knopf. pp. 688–689 + Plates 619–620, 653. ISBN 0-394-50824-6.
- Boulenger, G.A.. 1896. Catalogue of the Snakes in the British Museum (Natural History), Volume III., Including the...Viperidæ. Trustees of the British Museum (Natural History). (Taylor and Francis, Printers.) London. xiv + 727 pp. + Plates I.- XXV. (Crotalus horridus, pp. 578–580.)
- Schmidt, K.P., and D.D. Davis. 1941. Field Book of Snakes of the United States and Canada. G.P. Putnam's Sons. New York. 365 pp. (Crotalus horridus horridus, pp. 301-302 + Plate 33; Crotalus horridus atricaudatus, p. 302.)
- Conant, Roger & Collins, Joseph T. (1998). Reptiles and Amphibians of Eastern/Central North America. New York: Houghton Mifflin. ISBN 0-395-90452-8
- Crotalus horridus at Species at Risk Public Registry. Accessed 23 June 2008.
- Timber Rattlesnake Fact Sheet at NY State Dept. of Environmental Conservation. Accessed 8 February 2007.
- Furman, Jon (2007). Timber rattlesnakes in Vermont and New York: biology, history, and the fate of an endangered species. UPNE. p. 133. ISBN 978-1-58465-656-2.
- 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.
- U.S. Navy. 1991. Poisonous Snakes of the World. US Govt. New York: Dover Publications Inc. 203 pp. ISBN 0-486-26629-X.
- Medscape. Medscape (2004-08-16). Retrieved on 2013-01-05.
- Crotalus horridus horridus at Munich AntiVenom INdex. Accessed 27 March 2008.
- "Senate concurrent resolution 28 (bill status 2008 regular session)". West Virginia Legislature. Retrieved February 22, 2011.
- "Senate concurrent resolution no. 28". 1st session of the 80th legislature. West Virginia Legislature. 2008. Retrieved February 25, 2011.
- http://www.history1700s.com/articles/article1016.shtml[unreliable source?]
- Bryson, Bill. 2004. A Short History of Nearly Everything. New York: Broadway Books. p. 81.
- "Crotalus horridus atricaudatus". Integrated Taxonomic Information System. Retrieved 27 September 2006.
- 2001 Categories & Criteria (version 3.1) at the IUCN Red List. Accessed 13 September 2007.
- Indiana Legislative Services Agency (2011), "312 IAC 9-5-4: Endangered species of reptiles and amphibians", Indiana Administrative Code, retrieved 28 Apr 2012
Further reading 
- Brown CW, Ernst CH. 1986. A study of variation in eastern timber rattlesnakes, Crotalus horridus Linnae (Serpentes, Viperidae). Brimleyana 12: 57–74.
- Cist C. 1845. The Cincinnati Miscellany or Antiquities of the West. vol. 1. Cincinnati. 272 pp..
- Collins JT, Knight JL. 1980. Crotalus horridus Linnaeus. Timber rattlesnake. Catalogue of American Amphibians and Reptiles. 253.1 – 253.2.
- Gloyd HK. 1936. The cane-brake rattlesnake. Copeia 1935 (4): 175–178.
- Holt EG. 1924. Additional records for the Alabama herpetological catalogue. Copeia 1924 (136): 100–101.
- Klauber LM. 1936. Key to the rattlesnakes with summary of characteristics. Trans. San Diego Soc. Nat. Hist. 8 (2): 185–176.
- Klauber LM. 1956. Rattlesnakes: Their Habitats, Life Histories, and Influence on Mankind. 2 volumes. University of California Press, Berkeley. 1476 pp.
- Linnaeus C. 1758. Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, diferentiis, synonymis, locis. 10th Edition. Hollmiæ. Stockholm. (Crotalus horridus, p. 214.)
- Pisani GR, Collins JT, Edwards SR. 1972. A re-evaluation of the subspecies of Crotalus horridus. Trans. Kansas Acad. Sci. 75: 255–263.
- Schmidt KP. 1953. A check list of North American amphibians and reptiles. 6th ed. American Society of Ichthyologists and Herpetologists, Chicago. 280 pp.
|Wikimedia Commons has media related to: Crotalus horridus|
|Wikispecies has information related to: Crotalus horridus|
- Crotalus horridus at the Reptarium.cz Reptile Database. Accessed 12 December 2007.
- Timber Rattlesnake (Crotalus horridus) at Center for Reptile and Amphibian Conservation and Management. Accessed 8 February 2007.
- Timber Rattlesnake Crotalus horridus at Center for Reptile and Amphibian Conservation and Management. Accessed 8 February 2007.
- Timber Rattlesnake – Crotalus horridus at Herpnet.net, Reptiles and Amphibians of Iowa. Accessed 15 June 2007.
- Account of severe C. horridus envenomation at venomousreptiles.org. Accessed 12 December 2007.
- Canebrake Rattlesnake photos at Handyman Services in Durham, NC. Accessed 7 August 2007.
- Canebrake rattlesnake (Crotalus horridus) at Virginia Department of Game and Inland Fisheries. Accessed 7 August 2007.
- Snakes of Louisiana at Kingsnake.com. Accessed 7 August 2007.
- Timber Rattlesnakes Facts and Pictures.
- Timber Rattlesnake Fact Sheet at New York State Dept. of Environmental Conservation. Accessed 14 December 2008.
- Timber Rattlesnake, Natural Resources Canada