Archives of The Cold Blooded News

The Newsletter of the Colorado Herpetological Society

Volume 32, Number 7;   July, 2005

Western Hognose Snake Heterodon nasicus Baird & Girard, 1852

by Tom Eichhorst

The western hognose snake is found pretty much throughout New Mexico. There are generally three recognized subspecies: the nominate species, the western or plains hognose snake (Heterodon nasicus nasicus) found from southern New Mexico, through the Texas and Oklahoma panhandles to southern Canada; the dusty hognose snake (Heterodon nasicus gloydi Edgren, 1952), found from southwestern Texas (S.E. comer of New Mexico) to Oklahoma; and the Mexican hognose snake (Heterodon nasicus kennerlyi Kennicott, 1860), found from east central Mexico, to southern Arizona, New Mexico, and southwestern Texas. The western (or plains) hognose snake and the dusty hognose snake differ only in color and pattern and seem to intergrade where the ranges of the two meet. Thus the subspecies status of the dusty hognose is in question as it may be just a color form of the western (plains) hognose.

The western hognose snake is generally less than two feet long (a record 760mm (almost 30 inches) specimen of H. n. kennerlyi was collected in 1995 in southern New Mexico (Degenhardt et al., 1996), and has the thick body and distinctively upturned nose that mark this genus. The color/pattern generally consists of numerous irregular brown blotches (in various shades from light to dark brown, reddish to almost black) set against a tan background. The scales are keeled, giving the snake a rough, non-glossy appearance. The underside of the snake is smooth and shiny with undivided scales of light tan to yellow, or even orange, marked with black in various amounts from blotches to coloring almost the entire scale. This black on the underside of the snake is missing from the other two species of U.S. hognose snakes: the eastern hognose snake (Heterodon platirhinos) found from Texas, to the east coast and from Florida, to Maine; and the southern hognose snake (Heterodon simus) found from mid-Florida, to North Carolina, and to southern Mississippi. The eastern hognose is larger and darker in color with a solid black morph occurring. A three-foot long, rearing, hooded, hissing, and striking black hognose is an impressive sight and will cause the most intrepid herper to look twice to ensure he or she is not facing an exotic escapee. The southern hognose is similar in size and color to the western hognose, with fewer and darker blotches and no black on the ventral scales.

Hognose snakes of the genus Heterodon are only found in North America and Mexico (from southern Canada to central Mexico). Similar species from South America were included in the genus Heterodon at one time due to similar habits (feigning death), but are now in a distinct genus, Lystrophis. One of these, Lystrophis semicinctus, is a banded tri-colored (red, black, and white or yellow) snake similar to the color pattern found in some very popular kingsnakes.

Hognose snakes have rear fangs and a mild poison that has at times been implicated in serious medical problems for people who have been bitten. On the other hand, an actual bite from a hognose is a rare occurrence, as they will go to extreme measures when threatened to do everything but bite. A hognose encountered in the wild will remain still like most snakes and hope to be passed by. If this fails, the snake will usually attempt to flee. If prevented from leaving the scene, the snake will coil and flatten its neck, very much like a cobra. It will then present a "fearsome" appearance and proceed to hiss and strike at the intruder. But the strikes usually fall short and seldom involve a bite. The snake usually strikes with a closed mouth. If this does not resolve the situation the snake will often attempt to flee once again, and if prevented, it will begin writhing and thrashing around as if in great pain and the throes of death. The flipping, turning, writhing snake will then "die." This fake death is accomplished with the snake on its back, mouth agape, and sometimes food regurgitated and feces vented - a most convincing, if somewhat nauseous, display. If picked up, the snake will hang limply. The only sign of death missing are x's over the eyes! The scene is only spoiled if the snake is turned over right side up. In that case it will immediately flip back on its back to the "approved" death pose.

This dramatic defense mechanism of hognose snakes has resulted in a number of colorful common names, including: puff adder, hissing adder, blow viper, spreading adder, and hissing sand snake. Unfortunately, this behavior coupled with a common name that includes "adder," or the common mistaken identity for a copperhead or rattlesnake, causes a great number of these snakes to be killed out of ignorance and/or fear.

Hognose snakes are sexually mature in about three years and lay from five to two dozen eggs that hatch in approximately two months (depending upon temperature). They are found from river and stream valleys, to plains habitats, to mountains. They are rarely found under logs or trash, preferring to remain underground in harsh conditions and coming out to feed at night or during rains. Anurans, or frogs and toads, are the primary food of hognose snakes. This complicates captive care as they often refuse to feed on mice, sometimes even if the mouse is scented with a toad. This difficulty is rarely experienced with the western hognose as they have a wider range of prey and will eat mice (as well as frogs, toads, and snakes) in the wild. Most will readily convert to an all mice diet in captivity.

The western hognose is never a common find in the state, but always a nice find. These are good looking herps with straightforward captive care requirements. Care and breeding are similar to that needed for corn snakes or kingsnakes. Keep in mind that care should be exercised to avoid an inadvertent bite (due to feeding response) because serious reactions have been recorded from the venom of this mild mannered herp.

References:
Conant, Roger & Collins, Joseph T. 1998. Reptiles and Amphibians: Eastern/Central North America, Peterson Field Guide, Third Edition, (expanded), Houghton Mifflin Co., New York. pp.616.
Degenhardt, William G., Painter, Charles W., & Price, Andrew H. 1996. Amphibians and Reptiles of New Mexico, University of New Mexico Press, Albuquerque, N.M. pp. 431.
Mehrtens, John M. 1987. Living Snakes of the World in Color, Sterling Publishing Co., Inc. pp.480.