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Canadian Herpetological Society Société d'Herpétologie du Canada |
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Eastern Hog-nosed Snake
Heterodon platirhinos
Family: Colubridae
COSEWIC status:- Threatened
- Threatened
- Least Concern
Description
The Eastern Hog-nosed Snake has an unmistakable upturned snout, which gives this species its name. The coloration and patterning of this species is highly variable. Some individuals may have alternating dark blotches down the back and sides on a lighter background, which can be olive, tan, yellow, orange, brown or grey. Others may lack patterning altogether and are a solid colour, usually olive, grey or black. Although the blotches down the back and sides may be absent on some individuals, a large blotch behind each eye is always present, though it may not be readily apparent on black individuals. This species is thick-bodied and can flatten out its neck (like a cobra’s hood) during defensive displays. The scales of the eastern hog-nosed snake are keeled (ridged down the centre), and the underside of the tail is noticeably lighter in colour than the belly. These snakes can grow to just over a metre in length.
Similar Species
In Ontario, the Eastern Foxsnake, Massasauga and Milksnake also have blotches running down the back and sides, and the Northern Watersnake can have faint banding. All these species, however, lack the upturned snout, which among Ontario snakes is unique to the Eastern Hog-nosed Snake. It is also the only snake in the province that can flatten its neck into a “hood” as a cobra does.
Distribution
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In Canada, the Eastern Hog-nosed Snake is limited to southern and central Ontario. This species occurs throughout most of the eastern United States as far south as Florida and Texas.
Habitat
The Eastern Hog-nosed Snake inhabits fields, forests, forest clearings, shrubland, beaches and dune habitats. Along the eastern shore of Georgian Bay, it can also be found in rock outcrops, as long as other suitable habitat is available nearby. This species is generally found in habitats with sandy, well-drained soils, into which this snake burrows. Females lay eggs in burrows in sandy soil that the snake excavates with its upturned snout, rotting logs or under rocks or leaves. Eastern Hog-nosed Snakes hibernate underground below the frost line, often in burrows that they excavate in sandy soil.
Biology
The Eastern Hog-nosed Snake primarily breeds in the fall, though spring breeding also occurs. In late June or July, females lay between 7–40 eggs, which hatch after about two months, and the hatchlings are approximately 20 cm in length. Individuals of this species in Canada reach maturity in three to four years and can live for more than 20 years. The Eastern Hog-nosed Snake uses very mild venom to immobilize its prey which it injects through fangs at the back of its mouth. This species cannot inject venom into larger animals such as humans unless allowed to hold on for some time, and even then its venom is not dangerous to humans. When disturbed, the Eastern Hog-nosed Snake will raise its head, flatten its neck as a cobra does and hiss loudly, sometimes lunging toward the threat. This snake keeps its mouth closed during these bluff strikes. If this impressive display does not scare away a potential predator, the snake may roll onto its back and play dead with its mouth gaping and tongue hanging out, emit a foul-smelling odour and sometimes defecate or regurgitate food. This behaviour is meant to deter predators that do not eat dead or rotten animals. If the Eastern Hog-nosed Snake is turned over onto its belly, it will promptly flip onto its back and play dead again.
Threats
Habitat loss, especially shoreline development in beach and dune habitats, continues to threaten this species in Canada. Persecution by humans is a significant threat because uninformed people often kill Eastern Hog-nosed Snakes, mistaking their defensive display for that of a dangerous species. The Eastern Hog-nosed Snake is often mistakenly referred to as a Cobra or a Puff Adder, though neither of these venomous species occur in Canada, and the hog-nosed snake is harmless to humans. Road mortality is a threat to this species, especially in southern Ontario where road density and traffic volume are high.