Description: The Eastern Hog-nosed Snake is a moderately long, robust snake, with adults ranging from 20–33 inches (51–84 cm) in length. Individuals have a weakly upturned rostral scale at the tip of the snout. The coloration of Eastern Hog-nosed Snakes varies across their range, but in South Dakota, individuals typically have a light background that can range from light yellow to 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, without black markings. Scales are heavily keeled, and the anal scale is divided. Juveniles are similar in appearance to adults but can have bolder patterning and coloration. This species is similar in appearance to the Plains Hog-nosed Snake but can be easily differentiated by the lack of black pigmentation on the underside and a less sharply upturned snout (Plains Hog-nosed Snakes have black markings on the undersides and a sharply upturned snout).
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. In southeastern South Dakota, this species appears to be associated with cottonwood forests along the Missouri River.
Natural History: This is a primarily crepuscular species that feeds almost exclusively on frogs and toads. Enlarged, hinged fangs in the rear of the mouth can deliver mild venom to prey and deflate toads. When threatened, this species will flatten its head and neck creating a cobra-like hood. It will also hiss and thrash its head, and if agitation continues, will feign death by opening its mouth, rolling upside down, writhing, and releasing a foul-smelling musk until the threat passes. The Eastern Hog-nosed Snake is adapted for burrowing, using its upturned snout as a shovel and moving its head side to side. Individuals are active from April to October and will overwinter in burrows. Mating often takes place in late April when individuals have emerged from hibernation. Females lay 4–20 eggs in nests in sandy soils. Eggs hatch in late summer.
Species Distribution: This species can be found across much of the eastern United States, through the Great Lakes region, and into the southern Great Plains states.
South Dakota Distribution: Previously, Eastern Hog-nosed Snakes were thought to only occur in Clay and Union counties in the southeastern corner of South Dakota. More recently, records have been documented in Brule and Todd counties, which suggests that additional populations may occur along the Missouri River and in south-central South Dakota.
South Dakota Status: This species is listed as threatened by South Dakota Game, Fish and Parks. Any observations of this species should be reported to South Dakota Game, Fish and Parks (report observation).
Remarks: Though mildly venomous, Eastern Hog-nosed Snakes are not dangerous to people. This venom, produced by paired Duvernoy’s glands in the upper jaw, is a modified saliva that can immobilize prey. This species is docile, and bites are uncommon, though if bitten there may be slight swelling and discoloration at the site of the bite. Eastern Hog-nosed Snakes are sometimes called “adders” or “cobras” due to their tendency to flatten their necks.