Reptiles of North Carolina
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NC Records

Crotalus horridus - Timber Rattlesnake


Photo: N. Williamson, D. Williamson
Photo: Robert Wallace
Photo: BHI Conservancy Interns
Photo: K. Bischof
Taxonomy
Class: Reptilia Order: Serpentes Family: Viperidae Subfamily: Crotalinae
Taxonomic Comments: Crotalus is a diverse genus of more than 50 species of venomous rattlesnake found across North and South America, from southern Canada to Argentina.

Species Comments: Crotalus horridus, the Timber Rattlesnake, is one of two Crotalus (and one of three rattlesnakes) in North Carolina. It is found across the eastern and central United States, from Vermont to northern Florida and west to central Texas and Wisconsin. In North Carolina, it is found throughout the Mountains, parts of the Piedmont, and Coastal Plain. It is absent from large patches of northern and central North Carolina.

The two previously recognized subspecies, C. h. horridus and C. h. atricaudus (the "cane-brake" rattlesnake), are no longer valid. Allsteadt et al. (2006) showed that morphology is too variable and clinal to recognize subspecies, which are also not well-supported by molecular systematics.

The generic epithet Crotalus is derived from the Greek krotalon, "rattle". The specific epithet horridus is derived from the Latin horrid, "dreadful".

Taxonomic References: Collins and Knight (1980); Campbell and Lamar (2004); Allsteadt et al. (2006)
Identification
Description: Timber Rattlesnakes are large, heavy-bodied rattlesnakes with large heads and often long rattles. Adults are variable, with primary coloration ranging from pinkish, to gray, tan, brown, yellow, or black. Dorsal crossbands are typically black or brown, starting as blotches anteriorly and becoming more "wavy" crossbands posteriorly; the tail is almost entirely black. There is often a reddish or lighter dorsal stripe that may fade posteriorly. A thick, dark postorbital bar is usually present. The venter ranges from gray to yellow or pinkish with dark stippling and mottling.

Juveniles and neonates have conspicuous body patterns with distinct tail bands and an enlarged "button" tail tip.
Morphological Features: Timber Rattlesnakes typically have 23-25 heavily keeled dorsal scale rows at midbody. Ventral counts range from 154-183 (158-178 in NC specimens; Palmer and Braswell, 1995), with 17-31 (17-28) subcaudals and an undivided anal plate. Head scales are small, and counts are typically: 12-18 supralabials, 13-18 infralabials, 2 loreals, 2 preoculars, 4-5 post- and suboculars, and 2 nasals. Palmer and Braswell (1995) noted variation in scalation across their examined specimens.

Timber Rattlesnakes have a maximum recorded total length of 189.2 cm (74.5 inches). Palmer and Braswell (1995) reported a 167.6 cm male specimen from NC. Tail lengths account for only around 4-9% of total length. Males tend to have longer tails, more subcaudals, and fewer ventrals than females.

Timber Rattlesnakes are solenoglyphous, meaning they have large, elongated, hollow fangs that direct venom like a hypodermic needle. These fangs are extended out during a strike, and folded into the mouth when it is closed. Timber Rattlesnakes are dangerously venomous, and should not be handled. North Carolina populations have hemotoxic venom, meaning it works by attacking the blood and causing hemorrhaging; local swelling, pain, tissue necrosis, and hemorrhaging at the bite site are common symptoms, as are secondary infections. To date, no populations in North Carolina are known to have the neurotoxic "Type A" venom that is present in some Timber Rattlesnakes along the Atlantic Coast of South Carolina, Georgia, and Florida, as well as parts of Louisiana and Texas (Margres et al., 2021).

Timber Rattlesnakes are not aggressive, but when threatened will coil and rattle vigorously, and strike in defense. Bites have resulted in human fatalities, including the recent death of the renowned Timber Rattlesnake biologist William H. "Marty" Martin in 2020.
Technical Reference: Palmer and Braswell (1995); Ernst and Ernst (2003, 2011); Campbell and Lamar (2004)
Field Guide Descriptions: Beane et al. (2010).
Online Photos:    Google   iNaturalist   GBIF
Observation Methods: Timber Rattlesnakes are often found under cover objects, or encountered along roads.
Distribution in North Carolina
County Map: Clicking on a county returns the records for the species in that county.
Key Habitat Requirements
Habitat: Timber Rattlesnakes historically occupied an extremely wide range of habitats, including dry forests and rocky summits in the Mountains, hardwoods and mixed forests in the Piedmont, dry sandridges and wet peatlands in the Coastal Plain, and both cultivated and fallow fields throughout the state. Due to persecution by humans, however, they now occupy areas that are mostly remote from human habitations or more generally where human intrusion is fairly limited.
Life History and Autecology
Breeding and Courtship: Timber Rattlesnakes do not mature until at least 5 years old (males) or 7 years old (females), at snout-to-vent lengths greater than 100 cm. These snakes typically mate in summer and fall (July to October, most in August).
Reproductive Mode: Timber Rattlesnakes are ovoviviparous, giving birth to young enclosed in an amniotic sac; young are typically born August to October. Litters average 10–14 neonates.

Neonates average 33 cm in total length and weigh 23 g on average. Contrary to popular belief, neonate and juvenile rattlesnakes are not more venomous (or more likely to envenomate) than adults; juvenile venom glands are substantially smaller, and thus venom capacity is much smaller.
Terrestrial Life History: Timber Rattlesnakes are active both diurnally and nocturnally, and like many other species switch to more crepuscular/nocturnal activity as temperatures peak in the summer. When encountered in the field, it is usually beneath shelter or near logs in an ambush position; they may also be encountered crossing roads between habitat. Especially in areas with colder average climates, this species will hibernate communally, and are capable of traveling multiple kilometers from hibernacula to other places (Brown, in Ernst & Ernst, 2003). Females will stay with neonates for a week or more after birth, and neonates are apparently able to follow conspecific scent trails to communal hibernacula (Brown and MacLean, 1983; Reinert and Zappalorti, 1988). There are North Carolina records from every month, with most coming from summer and early fall (June–October).

In the Sauratown Mountains of the NC Piedmont (Stokes and Surry Co.), Sealy (2002) found Timber Rattlesnake home ranges averaged 24.5 hectares (245,000 m2), with larger averages for males (40 ha) than females (14 ha). Similar home range differences between males and females were recently found in Arkansas by Gallaher (2023), who noted average home ranges of 26 ha for males and 9 ha for females.
General Ecology
Adverse Environmental Impacts
Status in North Carolina
NHP State Rank: S3
Global Rank: G4
Status in North Carolina: SC

Photo Gallery for Crotalus horridus - Timber Rattlesnake

126 photos are available. Only the most recent 30 are shown.

Recorded by: C. Zurosky, K. Bischof
Transylvania Co.
Comment: 		Recorded by: K. Bischof, D. Schafer, N. Emerson, M. Galloway
Transylvania Co.
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Recorded by: K. Sanford, C. Griffin
Camden Co.
Comment: 		Recorded by: C. Pearson, K. Bischof
Transylvania Co.
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Recorded by: J. Mickey
Wilkes Co.
Comment: 		Recorded by: Amy Padgett
Bladen Co.
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Recorded by: K. Bischof
Transylvania Co.
Comment: 		Recorded by: K. Bischof
Transylvania Co.
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Recorded by: K. Bischof
Transylvania Co.
Comment: 		Recorded by: K. Bischof
Transylvania Co.
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Recorded by: K. Bischof, M. Briley
Transylvania Co.
Comment: 		Recorded by: T. Harris, K. Bischof
Transylvania Co.
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Recorded by: T. Harris, K. Bischof
Transylvania Co.
Comment: 		Recorded by: K. Bischof, A. Cook, F. Cook
Transylvania Co.
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Recorded by: J. Blanton
Gaston Co.
Comment: 		Recorded by: K. Bischof
Transylvania Co.
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Recorded by: K. Bischof
Transylvania Co.
Comment: 		Recorded by: K. Bischof
Transylvania Co.
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Recorded by: K. Sanford, A. Brown
Camden Co.
Comment: 		Recorded by: A. Slack
McDowell Co.
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Recorded by: K. Bischof
Transylvania Co.
Comment: 		Recorded by: K. Bischof
Transylvania Co.
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Recorded by: J.Buie
Stokes Co.
Comment: 		Recorded by: J.Buie
Stokes Co.
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Recorded by: Jim Petranka
Buncombe Co.
Comment: 		Recorded by: K. Bischof
Transylvania Co.
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Recorded by: K. Bischof
Transylvania Co.
Comment: 		Recorded by: K. Bischof
Transylvania Co.
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Recorded by: A. Page, C. Agule
Camden Co.
Comment: 		Recorded by: K. Bischof
Transylvania Co.
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