Plains Hog-nosed Snake Heterodon nasicus

NON-VENOMOUS

Family: Colubridae

General Description: The Plains Hog-nosed Snake is a moderately long, robust snake, with adults ranging from 15–26 inches (38.1–66.0 cm) in length. Like other hog-nosed snakes, the Plains Hog-nosed Snake has an upturned rostral scale at the tip of the snout that is the source of their name. Background coloration is typically light brown or tan and a series of brown dorsal and lateral blotches run the length of the body. The underside of individuals is tan or light yellow in coloration with black markings. Scales are heavily keeled. Juveniles are similar in appearance to adults. The Plains Hog-nosed Snake is similar in appearance to the Eastern Hog-nosed Snake but can be easily differentiated by the presence of black pigmentation on the belly (Eastern Hog-nosed Snakes lack black pigmentation) and a more sharply upturned snout (Eastern Hog-nosed Snakes have a less sharply upturned snout).

Behavior: Plains Hog-nosed Snakes are a primarily crepuscular species, and feeds primarily on frogs and toads, though will also consume birds, mammals, and eggs. 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 Eastern 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 52–64 days.

Habitat: The Plains Hog-nosed Snake is primarily found in grasslands with loose, sandy soils, though can be found associated with aquatic habitats such as rivers and reservoirs in their range.

Species Range: This species can be found across much of the central United States, throughout the Great Plains and east of the Rocky Mountains. Isolated populations of Plains Hog-nosed Snakes exist throughout Illinois, Iowa, Missouri, and Minnesota.

South Dakota Range: Plains Hog-nosed Snakes are only found throughout the state of South Dakota, though appear to be more abundant in the western half of the state.

South Dakota Status: This species is not listed or monitored by South Dakota Game, Fish and Parks.

Account written by Drew R. Davis and Sydney R. Hancock

Distribution Map
Distribution map of Plains Hog-nosed Snake (Heterodon nasicus)

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.

Photographs
Plains Hog-nosed Snake (Heterodon nasicus)
Plains Hog-nosed Snake (Heterodon nasicus)
Plains Hog-nosed Snake (Heterodon nasicus)
Plains Hog-nosed Snake (Heterodon nasicus)