Heterodon nasicus Baird and Girard, 1852
Plains Hog-nosed Snake
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Basis for Listing
The range of the plains hog-nosed snake is confined to central North America, ranging from southern Canada through the central United States to northern Mexico. In Minnesota, it has been found at widely scattered localities in a limited number of counties. The plains hog-nosed snake was listed as a special concern species in Minnesota in 1984 primarily due to loss of habitat. However, collection for the pet trade is also a concern.
The plains hog-nosed snake is a medium sized, stout-bodied snake. Adults range from 38-63.5 cm (15-25 in.) long, with the record size being 100.6 cm (39.6 in.) long (Conant and Collins 1998). The dorsal ground color is light yellowish-tan to grayish-olive, or even a rich brown. There are a series of dark oval middorsal blotches with smaller ones along the sides. The ventral surface is white to yellowish with masses of dark pigment, sometimes with yellow or orange mixed in. The head is marked with long dark blotches, and the snout is sharply upturned and used for digging. The scales are keeled and the anal plate is divided. This species resembles its close relative, the eastern hog-nosed snake (Heterodon platirhinos), but the eastern hog-nosed snake has a less upturned snout, and the underside of its tail is lighter than the rest of the belly (Oldfield and Moriarty 1994). A hog-nosed snake will flatten its head like a cobra when approached and it may hiss and strike or feign death when harassed.
The plains hog-nosed snake is a habitat specialist, preferring open, sparsely vegetated habitats on well-drained soils. Dry prairie habitats are preferred, but it may also inhabit oak savanna habitats. Pocket gopher burrows are also frequently utilized.
Biology / Life History
Plains hog-nosed snakes overwinter below the frost-line in mammal tunnels or self-dug burrows, and emerge from hibernation early in the spring (Oldfield and Moriarty 1994). Breeding usually takes place in mid-April through May (Oldfield and Moriarty 1994). Females lay 2-24 eggs (Ernst and Barbour 1989) in late May to early July, and young emerge after 50-65 days (Oldfield and Moriarty 1994). The young are 17-19 cm (6.7-7.5 in.) long at hatching (Ernst and Barbour 1989).
Conservation / Management
The major threat to the plains hog-nosed snake is habitat loss caused primarily by agriculture and urban sprawl. Snake populations that occur near urban areas are threatened with extirpation when roads and developments fragment their open, grassland habitat. In residential areas, people who encounter plains hog-nosed snakes may be frightened by their cobra-like defense posture, and kill them. Although popular as pets, most hog-nosed snakes kept as pets today are captive bred. Wild-caught individuals are not as adaptable to captivity.
Conservation Efforts in Minnesota
While habitat loss is a significant threat to plains hog-nosed snake populations in Minnesota, protection and management of grasslands and savannas helps enhance remaining habitats.
Conant, R., and J. T. Collins. 1998. A field guide to reptiles and amphibians of eastern and central North America. Third edition. Houghton Mifflin Company, New York, New York. 616 pp.
Ernst, C. H., and R. W. Barbour. 1989. Snakes of eastern North America. George Mason University Press, Fairfax, Virginia. 282 pp.
Oldfield, B., and J. J. Moriarty. 1994. Amphibians and reptiles native to Minnesota. University of Minnesota Press, Minneapolis, Minnesota. 237 pp.
Wright, A. H., and A. A. Wright. 1957. Handbook of snakes of the United States and Canada. 2 Volumes. Comstock Publishing Associates, Ithaca, New York. 1105 pp.