Timber Rattlesnake
Crotalus horridus • Order: Squamata, Suborder: Serpentes, Family: Viperidae, Subfamily: Crotalinae, Genus: Crotalus, Species: Crotalus horridus
Eastern United States, from southern New Hampshire to north Florida, and west to southeastern Nebraska and east Texas. They have been extirpated from much of the northern part of their range.
Look up Timber Rattlesnake in the Snake Encyclopedia →Venomous Status
Venomous; Solenoglyphous (large, retractable fangs located at the front of the maxilla).
Danger Level
Extremely Dangerous; this is one of North America's most dangerous snakes due to its large size, long fangs, and high venom yield, though it is generally shy and avoids confrontation.
Family
Order: Squamata, Suborder: Serpentes, Family: Viperidae, Subfamily: Crotalinae, Genus: Crotalus, Species: Crotalus horridus
Conservation
IUCN Least Concern globally, but many northern states list it as Threatened or Endangered due to habitat fragmentation, road mortality, and historic persecution.
Physical Description
Heavy-bodied pit viper with a broad, triangular head. Coloration is yellowish-brown, grey, or tan with dark brown or black crossbands often in a 'chevron' or 'V' shape. A distinct dark stripe often runs behind the eye. Scales are heavily keeled.
Size & Dimensions
The specimen pictured appears to be an adult, approximately 3-4 feet in length. The typical range for the species is 36-60 inches (91-152 cm), with rare records exceeding 70 inches.
Habitat
Upland deciduous or mixed deciduous-coniferous forests, often with rugged terrain and rocky outcroppings. They require communal dens in rock crevices for overwintering in northern climates and use sun-exposed basking sites.
Behavior & Temperament
Generally docile and cryptic, relying on camouflage to remain undetected. Usually rattles as a warning when approached too closely or disturbed. Diurnal in spring/fall and increasingly nocturnal during hot summer months.
Diet & Feeding
Primarily small to medium-sized mammals (squirrels, chipmunks, mice, rats) and occasionally birds. They are ambush predators that strike and release prey, tracking it via scent after it dies.
Reproduction
Viviparous (gives birth to live young); females breed every 2-6 years depending on local resource availability and climate. Litters typically consist of 5-14 neonates born in late summer.
Venom Profile
Variable by region; primarily hemotoxic and cytotoxic, causing tissue damage and necrosis. Some southern populations possess 'Type B' neurotoxic venom (Canebrake Rattlesnake phenotype).
Look-alikes
Eastern Diamondback (Crotalus adamanteus) which has diamond patterns; Northern Copperhead (Agkistrodon contortrix) which lacks a rattle and has 'hourglass' patterns; Eastern Hognose (Heterodon platirhinos) which mimics rattlesnakes but has an upturned snout.
Conservation Status
IUCN Least Concern globally, but many northern states list it as Threatened or Endangered due to habitat fragmentation, road mortality, and historic persecution.
Cultural Significance
Historically used as a symbol of the American Revolution (Gadsden Flag, 'Don't Tread on Me'). Key ecological role in controlling rodent populations, which helps limit the spread of Lyme disease.
Notable Features
Distinctive keratinous rattle at the end of the tail used as a warning signal; heat-sensing pits located between the eye and nostril allow for accurate strikes in total darkness.