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Plains Hog-nosed Snake

Heterodon nasicus

Family: Colubridae

COSEWIC status:
  • Not Assessed
SARA status:
  • No Status
IUCN status:
  • Least Concern

Description

The Plains Hog-nosed Snake is thick-bodied and is brown, tan or grey with large dark blotches down the back and several rows of smaller blotches down the sides. It has a dark bar that extends from each eye to the back of the mouth and a dark spot on each side of the head that extends onto the neck. As per its name, this species has a distinct upturned and pointed snout. The scales are keeled. The belly is largely black with yellow or whitish blotches. Adults typically do not exceed 1 m in length.

Similar Species

Other prairie species with bold blotches are the Bullsnake and the Prairie Rattlesnake. However, neither of these species has an upturned snout. Further, the Prairie Rattlesnake usually has a rattle at the tip of the tail and a distinctly triangular head.

Distribution

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Within Canada, the Plains Hog-nosed Snake is found in southern Manitoba, Saskatchewan and Alberta. It also occurs throughout the central plains in the U.S. and into Mexico.

Habitat

Plains Hog-nosed Snakes primarily inhabit grasslands, savannah and scrubland, but can also be found in woodlands, desert and river valleys. This species is typically found in areas with sandy or gravelly soils that it can burrow into. These snakes overwinter underground below the frost line in burrows that they excavate or in mammal burrows. The eggs are deposited in burrows that are excavated by the female in loose sand.

Biology

Females reach maturity at two to four years of age and males at one or two years or age. Individuals of this species can live for over twenty years. Mating occurs in the spring and females lay 2–23 eggs in late June or July. The eggs hatch in late summer or early fall and hatchlings are about 17 cm in length. The Plains Hog-nosed Snake hunts during the day and eats toads, frogs, salamanders, lizards, other snakes, small rodents and some invertebrates. It has specialized teeth at the back of the mouth that deliver mild venom, which is produced in the Duvernoy’s gland; however, this species is not harmful to humans. These teeth are also very effective at puncturing toads that have inflated themselves in self defense. When threatened, this species may put on one of two impressive performances: it may flatten out its neck into a hood (much like a cobra), rear up, hiss and pretend to strike or it may play dead by rolling onto its back with its mouth gaping and tongue hanging out, defecating, and emitting a foul odor.

Threats

The conversion of natural grasslands to agricultural uses reduces the available habitat for this species in Canada. Road mortality may contribute to population declines where roads bisect this species’ habitat, especially in areas where traffic volume is high. Human persecution also results in additional mortality to this species because people misidentify Plains Hog-nosed Snakes as rattlesnakes or incorrectly believe them to be deadly “puff adders” or cobras, neither of which occur in Canada. Consequently, public education is important to help prevent the unnecessary death of these snakes.

Additional Information About This Species In Canada