Plains Hog-nosed Snake

Heterodon nasicus

Plains Hog-nosed Snake

Distribution in Wyoming

 

 

 

 

 

 

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The distribution of the Plains Hog-nosed Snake cuts a swath through the Great Plains from southern Canada into Montana and North Dakota, and south into New Mexico, Texas, Oklahoma, and northern Mexico. In Wyoming it is found in the grassland communities of the prairie life zone below 6,000 feet, from the Big Horn Basin and Powder River Basin to the southeastern corner of the state. It has a preference for sandy and friable soils providing easy burrowing.

These diurnal snakes are adapted to digging and life underground (fossorial). They are active from April into October, dining primarily on toads with an occasional side dish of frogs, small birds, and rodents. Their rear teeth are enlarged and used to puncture the inflated bodies of toads to allow easier swallowing. These teeth are un-grooved (not fang like) and aid in injecting a toxic saliva into their prey to help with digestion. They rarely bite when handled and the saliva is not toxic to humans—though it may cause some inflammation and swelling similar to an allergic reaction.

Plains Hog-nosed Snake Plains Hog-nosed Snake

Their first response to a troublesome situation is to coil, flatten their head and then hiss and make several feeble and noncommittal strikes—with the mouth open or closed. This behavior resembles the actions of rattlesnakes and has erroneously earned the snake additional common names such as sand-viper and puff-adder—often resulting in their needless and unwarranted death. Occasionally they will tuck their head under the coils and strike out with their tail.

When frightened or antagonized, these snakes are well known for their habit of “playing possum.” They display convulsive and withering movements, roll on to the back, mouth gape and expose the tongue, regurgitate or foul the mouth with soil and debris, and defecate. (It’s really a nice performance.) If they are turned right-side up they quickly roll on to the back again and then continue playing dead. If left undisturbed for a few minutes they eventually right themselves and crawl away.

Plains Hog-nosed Snake Plains Hog-nosed Snake

It is a small to medium sized snake with a total length (TL) in the range of 18-24 inches. Characteristic of the species is the upturned, shovel-like snout formed from the rostral scale. It has a stocky body with a thick neck and broad head. The dorsal scales are keeled and overlapping; the ventral scales are smooth, rectangular, and form a series of plates along the body. The anal plate is divided. The background is tan and brown with a midline row of large dark blotches along the length of the body; these are bordered along each side with a row of smaller blotches. The belly is white or cream with a wide center strip of black or checkered black-and-white. The head has five dark bands radiating out from top-dead-center.

Plains Hog-nosed Snake Plains Hog-nosed Snake

Mating occurs in May and males use smell to follow sent trails left by females. They are oviparous and lay a clutch of 5-15 white, oval, leathery eggs in June or July. Females are believed to lay every other year. Hatching requires a 50-60 day incubation period. Males reach sexual maturity in the 2nd year, females in the 3rd year.