Western Hognose Snake
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Three subspecies of the Western Hognose Snake
(Heterodon nasicus) are currently described. The Plains Hognose Snake is the subspecies found in Alberta, where its range enters into the extreme southeastern corner of the province. In 1996, the Western Hognose Snake was placed on Alberta's
Blue List of species thought to be at risk of declining to
non-viable population levels in the province. The species had been ranked as a
Red List species in 1991 but was updated in 1996 due to recent increases in new Alberta records. Nevertheless, the lack of information on Plains Hognose Snakes makes it difficult to assess current population trends.
The habitat of the Plains Hognose Snake in Alberta and Saskatchewan falls within the
Grassland Natural Region of the High Plains, the latter being the third tier of the Interior Plains of Canada. The High Plains include Alberta's entire prairie region. This area has been described as either short or
mixedgrass prairie, or a combination of the two. This semi-arid region is subject to moderately long, hot but variable summers, and moderately long, and at times extremely cold, winters.
Records from Alberta suggest that Plains Hognose Snakes prefer predominantly or completely sandy locations within the grasslands region. Two records, the first from the Milk River south of Comrey, and the second from the
Comrey breaks, place this snake on the coulee rim, grassland/badlands
ecotone, where clay soil and/or gravel, scattered rocks, jumbled boulders and ground juniper are the prominent features. In Alberta, the apparent preference of Plains Hognose Snakes for sandy soils results in these habitats being most frequently searched by biologists. Recent records, however, show that the Plains Hognose Snake occurs in more diverse habitat than was formerly believed. For example, they may also be found near wetlands.
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The Plains Hognose Snake is a small to medium sized, heavy-bodied snake
with a brownish-gray body colour and three to five rows of darker brown blotches down its dorsal and lateral surfaces. The pattern and colouration resembles that of some specimens of the Prairie Rattlesnake. The underside is completely black, or black checkered with yellow or white. At maturity, the females are larger than the males, and the males have relatively longer tails in comparison to their bodies. The fangs are at the rear of the mouth and the venom is not normally considered dangerous to humans. Plains Hognose Snakes are not aggressive towards humans, and
rarely bite.
In Alberta, the Plains Hognose Snake emerges from hibernation in late April or early May and enters hibernation in the fall in late September, and likely into early October. Plains Hognose Snakes are
diurnal, and appear to be most active on sunny days in Alberta, when air temperatures are between 10 and
20 degrees Celsius. They are rarely seen when temperatures exceed 20
degrees Celsius.
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Plains Hognose Snakes feed on many organisms in the wild. It is generally agreed upon, however, that they exhibit, like all the Heterodon, a preference for toads of all kinds. Other prey items include frogs, salamanders, turtle eggs, lizards, small birds, rodents,
and other snakes. The fact that hognose snakes frequently feed on rodents, combined with the frequency with which they are found among Pocket Gopher colonies, suggests that they may include newborn examples of this rodent in their diets, as well as, perhaps, the young of the
Thirteen Lined Ground Squirrels.