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Canadian Herpetological Society





Société d'herpétologie du Canada



Hypsiglena chlorophaea deserticola
Northern Desert Nightsnake / Couleuvre nocturne


Nightsnake

The Nightsnake, and other slender, rear-fanged snakes, which were included within the Family Colubridae, have recently been placed in the Family Dipsadidae.

Description
The Nightsnake is beige, yellowish or gray with numerous dark brown or gray blotches on the back and sides. Although it is relatively similar to other blotched snakes, the Nightsnake has a characteristic large blotch on each side of the neck. The pupils of the eyes are also vertical. The Nightsnake can grow to over 60 cm in total length.

Confusing Species
The Nightsnake is similar to other blotched snakes of British Columbia. The Wandering Gartersnake has a yellow or brown stripe down the length of the back. The Great Basin Gophersnake grows to a much larger size. Small individuals can be confused with the Nightsnake, but the Gophersnake has a round pupil. The Northern Pacific Rattlesnake has the same basic pattern of the Nightsnake, as well as the vertical pupil. It can be distinguished from the Nightsnake by the presence of the rattle, and the characteristic triangular head.

Distribution
The Nightsnake appears to be limited to only the southern portions of the Okanagan Valley, although it was only first discovered in Canada in 1980. It may also be found farther north in the Okanagan in similar areas. The Canadian populations may be connected with populations in Washington state. The majority of the range is in the southwestern US and south into Mexico and central America.

Habitat
The Nightsnake is mainly limited to hot, dry areas, with near desert conditions. It is found in both rocky and sandy areas. The Nightsnake is frequently found under rocks or boards.

Reproduction
Breeding appears to occur in the spring. Females lay 4-6 eggs in late spring to early summer. The eggs hatch in approximately two months. Hatchlings vary greatly in size apparently ranging from 13-19 cm in total length.

Natural History
Nightsnakes are mainly nocturnal and therefore rarely encountered. Most of the day is spent under cover. The Nightsnake has enlarged grooved teeth at the back of the upper jaw for holding prey such as frogs. The snake's saliva is mildly toxic and immobilizes the prey. Nightsnakes will even consume juvenile Western Rattlesnakes.

Conservation Concerns
The Nightsnake is limited to only a small area in southern BC. Virtually nothing is known about the ecology of the species this far north. To date only a few Night Snakes have even been seen in BC. The Nightsnake has been designated Endangered by COSEWIC