Eastern Hog-nosed Snake Heterodon platirhinos - Threatened


Family: Colubridae

General Description: The Eastern Hog-nosed Snake is a moderately long, robust snake, with adults ranging from 29–36 inches (73.7–91.4 cm) in length. Like other hog-nosed snakes, the Eastern Hog-nosed Snake has an upturned rostral scale at the tip of the snout that is the source of their name. The coloration of Eastern Hog-nosed Snakes varies across their wide range, but in South Dakota individuals are typically have a light background coloration that can range from light yellow, tan, or brown, with a series of dorsal and lateral dark brown or black blotches. Typically, a large black marking is present on each side of the neck. Some individuals will have faded blotches giving it an unmarked appearance. The underside of individuals is cream, tan, or light yellow in coloration without black markings. Scales are heavily keeled. Juveniles are similar in appearance to adults but can have bolder patterning and coloration. The Eastern Hog-nosed Snake is similar in appearance to the Plains Hog-nosed Snake but can be easily differentiated by the lack of black pigmentation on the belly (Plains Hog-nosed Snakes have black pigmentation) and a less sharply upturned snout (Plains Hog-nosed Snakes have a sharply upturned snout).

Behavior: Eastern Hog-nosed Snakes are a primarily crepuscular species, and feeds almost exclusively on frogs and toads. This species has enlarged, hinged fangs in the rear of the mouth than can deliver mild venom to prey (this venom is harmless to humans). This species (like the Plains Hog-nosed Snake) has elaborate anti-predator displays. When threatened, this species will flatten its head and neck creating a cobra-like hood (hog-nosed snakes are sometimes called “adders” or “cobras” incorrectly). Additionally, this species will hiss and thrash its head. If agitation continues, individuals will “feign death” by opening its mouth, rolling upside down, writing, and releasing a foul-smelling musk, then will go limp until predatory threats pass.

Reproduction: Mating often takes place in late April when individuals have emerged from hibernation. Females will then lay 4–20 eggs in nests in sandy soils that hatch in late summer.

Habitat: The Eastern Hog-nosed Snake is primarily found in river floodplains and other riparian woodlands. These snakes prefer areas that are sparse in vegetation and have sandy soils that accommodate digging behaviors.

Species Range: This species can be found across much of the eastern United States, through the Great Lakes region and southern Great Plains states.

South Dakota Range: Eastern Hog-nosed Snakes are only found in the southeast corner of South Dakota in Clay and Union counties.

South Dakota Status: This species is listed as threatened by South Dakota Game, Fish and Parks. Any sightings of this species should be reported to South Dakota Game, Fish and Parks (report observation).

Account written by Drew R. Davis

Distribution Map
Distribution map of Eastern Hog-nosed Snake (Heterodon platirhinos)

County level distribution of this species in South Dakota. Map generated from data collected from voucher specimens and photographic records. See About for additional information.

Eastern Hog-nosed Snake (Heterodon platirhinos)
Eastern Hog-nosed Snake (Heterodon platirhinos)
Eastern Hog-nosed Snake (Heterodon platirhinos)