Western Rat Snake (or Black Rat Snake)
Pantherophis obsoletus • Order: Squamata, Suborder: Serpentes, Family: Colubridae, Subfamily: Colubrinae, Genus: Pantherophis, Species: P. obsoletus
Central and Eastern United States, specifically from the Mississippi River west to the Rocky Mountains and north into southern Canada. In the Eastern US, they integrate with P. alleghaniensis and P. spiloides.
Look up Western Rat Snake (or Black Rat Snake) in the Snake Encyclopedia →Venomous Status
Non-venomous (Aglyphous)
Danger Level
Harmless; though they may bite if cornered or handled, the bite is medically insignificant and they have no venom.
Family
Order: Squamata, Suborder: Serpentes, Family: Colubridae, Subfamily: Colubrinae, Genus: Pantherophis, Species: P. obsoletus
Conservation
Least Concern (IUCN); however, they face localized threats from habitat loss and intentional killing due to being mistaken for venomous snakes.
Physical Description
Large, powerful body with weakly keeled scales. Adults are often dark black or grey with faint saddle-like patterns or white visible between the scales when the body is distended. The belly is white or yellowish with dark mottling. The head is wider than the neck and the pupils are round.
Size & Dimensions
The specimen in the photo appears to be a mid-sized adult, roughly 3-4 feet long. The species typically ranges from 3 to 5 feet, though record lengths exceed 8 feet (approx 2.5 meters).
Habitat
Highly adaptable; found in hardwood forests, swamps, rocky hillsides, and frequently near human dwellings such as barns and gardens. Found at elevations from sea level to over 1300 meters.
Behavior & Temperament
Primarily diurnal or crepuscular, though they become nocturnal in summer. They are excellent climbers (often found in trees) and tend to 'freeze' or 'kink' their bodies when threatened. They may rattle their tail in leaf litter to mimic rattlesnakes.
Diet & Feeding
Generalist predators that use constriction. They feed primarily on rodents (rats and mice), birds, and eggs. They are active foragers often referred to as 'mousers.'
Reproduction
Oviparous; females lay clutches of 10 to 20 eggs in the summer (June-July), which hatch in late summer or early autumn. Nesting sites include rotted logs, leaf litter, and mulch piles.
Venom Profile
Non-venomous - no medically significant venom.
Look-alikes
Commonly confused with the Northern Copperhead (Agkistrodon contortrix) due to pattern, or the Timber Rattlesnake (Crotalus horridus). Distinguished by round pupils, lack of heat-sensing pits, and absence of a rattle.
Conservation Status
Least Concern (IUCN); however, they face localized threats from habitat loss and intentional killing due to being mistaken for venomous snakes.
Cultural Significance
Highly valued by farmers and gardeners for natural pest control of rodent populations. In local folklore, they are often incorrectly thought to interbreed with rattlesnakes.
Notable Features
Renowned for their climbing ability, they can scale vertical tree trunks using the sharp angles of their ventral scales. They often exhibit a characteristic 'kinked' pose when resting or feeling threatened.