Western hognose snake

Identification

The western hognose snake is small and stout, with a sharply upturned, keeled snout that it uses like a spade for digging^4,5. Its body is grey, tan, yellowish or light brown, with 23–50 dark brown blotches down the back and rows of smaller spots along the sides⁴. The belly and the underside of the tail are largely jet black, sometimes edged with yellow or orange^4,5. The scales are keeled⁴.

Adults usually measure 38–63.5 cm, and the largest recorded reached 1.0 m (100.3 cm)⁴. In Colorado few grow longer than about 50 cm⁸.

Distribution

This snake lives on the Great Plains, from southern Alberta, Saskatchewan and Manitoba south through Montana, the Dakotas, Nebraska, Kansas and eastern Colorado to Oklahoma, Texas and New Mexico, and east to Minnesota, Iowa and Illinois^1,5.

The Mexican hognose snake (Heterodon kennerlyi) of southern Arizona, southern New Mexico, southern Texas and Mexico was long treated as a subspecies of this snake, but The Reptile Database now lists it as a separate species, so H. nasicus does not occur in Mexico^1,2. The dusty hognose snake of Texas and Oklahoma, sometimes called H. gloydi, is kept as a subspecies, H. n. gloydi, by both The Reptile Database and the 2025 list of North American names^1,3. In Illinois, one population in Kankakee County was introduced by people⁶.

Habitat

The western hognose snake prefers plains and savanna with loose, well-drained sandy or gravelly soil that it can burrow into⁵. In Colorado it lives in sandhills, plains grassland and sandy floodplains, often near streams, irrigation ditches and ponds⁸. In Illinois it is a snake of sand prairies and savannas⁶. It can also live in lightly farmed areas where the soil suits it, but intensive cropping reduces its habitat⁵.

Behaviour

This snake is active by day, mostly in the morning and late afternoon, and spends the night and other quiet periods buried in loose soil^4,5. It does not gather in shared winter dens; each snake digs its own burrow below the frost line⁵.

When disturbed it usually crawls away or hides its head under its coils⁴. If pressed, it flattens its neck into a hood-like shape, hisses loudly and makes short strikes with its mouth closed⁴. If that fails, it may writhe, bring up its last meal, roll onto its back and play dead for up to five minutes⁴. If turned the right way up, it rolls straight back over⁵.

Diet

The western hognose snake finds much of its food by smell and digs it out with its snout^4,5. It eats toads, the eggs of reptiles such as turtles, lizards and snakes, and also takes frogs, rodents and birds^4,5. Enlarged teeth at the back of its upper jaw help it hold and deflate toads that puff themselves up⁵.

Reproduction

The western hognose snake lays eggs. It usually mates in May, although some mating happens in autumn^4,5. Clutches of 4–23 eggs, about 9 on average, are laid in July a few centimetres below the soil surface, and females often breed only every other year⁴. The eggs hatch after 50–60 days, and the hatchlings are 14–20 cm long^4,5. Males mature at 2–3 years old and females at 3–4 years⁵.

Venom and medical significance

The western hognose snake is rear-fanged, with enlarged teeth at the back of its upper jaw, and its saliva is toxic to its prey^5,6. Wild snakes almost never bite, and nearly all recorded bites have happened while people were feeding pet snakes^4,5. When a snake holds on, the bite can cause painful swelling, bruising, blisters and swollen lymph nodes, which took about five months to clear in one case⁹. In another case, a woman also had a temporary drop in blood platelets¹⁰. Experts label it differently: Colorado’s wildlife agency calls it venomous but not dangerous to people⁸, while a 2009 review concluded that hognose snakes can occasionally cause medically significant bites but should not be considered dangerous or venomous⁹. Anyone bitten should seek medical care¹⁰.

Conservation

The western hognose snake is listed as Least Concern on the IUCN Red List (assessed in 2007)¹¹. It has declined in some areas and is listed as Threatened in Illinois and as a Species of Concern in Montana^5,6. Likely threats include the conversion of prairie to farmland, road deaths while snakes bask on roads, people killing them in the mistaken belief that they are rattlesnakes, and collection for the pet trade⁵.

Similar species

Because of its blotched pattern and loud hissing, the western hognose snake is often mistaken for a rattlesnake and killed^4,5. Rattlesnakes such as the prairie rattlesnake have a similar blotched pattern, but the hognose has a sharply upturned snout and no rattle⁵.

The eastern hognose snake (Heterodon platirhinos) is similar, but the underside of its tail is always lighter than its belly, while the western hognose has a mostly black belly and tail^6,7. The Mexican hognose snake replaces this species further south-west and was split from it on the basis of scale differences^1,2.

These differences are not a safe basis for handling any snake. Keep your distance from every snake you cannot identify.

In captivity

The western hognose snake is fairly docile and is popular in the pet trade, where it has been bred into dozens of colour forms⁸. Captive snakes have lived for nearly 20 years^4,5. Because most bites happen at feeding time, captive hognose snakes should be handled with care, especially when food is offered^4,9.