Desert Nightsnake (Hypsiglena chlorophaea) is a relatively small snake (up to 61 cm). The background colour is light brown or grey with a line of dark brown blotches, often in pairs, down the middle of the back and two lines of smaller blotches on each side. It has a glossy, pearl finish compared to other local snakes. Three larger blotches occur on the back of the neck, which are sometimes connected forming a rough ?W? shape. The eye has a vertically elliptical pupil. The belly is whitish or yellowish. Desert Nightsnake is a rear-fanged venomous snake, but the venom is not known to be dangerous to humans and this species seldom bites when captured.
This species was first reported from Canada in 1980 and only 71 observations had been reported up to 2015. In Canada, Desert Nightsnake is known only from British Columbia in the Okanagan Valley, south of Penticton to the United States border, and in the Lower Similkameen Valley. The species occurs in the Bunchgrass, Ponderosa Pine, and Interior Douglas-fir biogeoclimatic zones below 1000 m elevation. Habitat use is concentrated in talus and rock outcrop where its main prey species, Western Skink (Plestiodon skiltonianus), is found; however, it also uses grassland, shrub?steppe, and open ponderosa pine (Pinus ponderosa) and Rocky Mountain Douglas-fir (Pseudotsuga menziesii var. glauca) forests. Their active season is from March through October.
The Desert Nightsnake was designated as Endangered by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) in 2011 owing to its small distribution, habitat loss, and fragmentation primarily attributed to expanding urban and agricultural developments and vehicle-caused mortality. It is listed as Endangered in Canada on Schedule 1 of the Species at Risk Act. In British Columbia, the Desert Nightsnake is ranked S1 (?critically imperiled?) by the Conservation Data Centre and is on the provincial Red List. The B.C. Conservation Framework ranks the Desert Nightsnake as a priority 1 under goal 3 (maintain the diversity of native species and ecosystems). It is protected, under the provincial Wildlife Act, from capture and killing. Recovery is considered to be biologically and technically feasible. Because of difficulties in detecting the species, an ecosystems protection approach to recovery, using habitat for surrogate species such as Western Skink and Western Rattlesnake (Crotalus oreganus), is required to augment species specific actions.
The overall province-wide threat impact for this species is High. This overall threat impact considers the cumulative impacts of multiple threats. Primary threats include direct harm from road mortality and habitat loss from housing development. Lower-ranked threats include habitat loss or degradation from agriculture, quarrying, and fire suppression, and direct harm from invasive non-native species.
The recovery goal is to maintain or increase the abundance of Desert Nightsnake within its known geographic range in British Columbia and to maintain or increase connectivity within and between occupied areas.
The following objectives are necessary to meet the recovery goal and facilitate species recovery.
1. Identify new den (hibernation) sites, secure occupied sites and ensure connectivity is maintained between foraging/migration, shedding and dispersal habitats throughout the species? known range in British Columbia.
2. Reduce road mortality to a level that will not affect population viability.
3. Address knowledge gaps related to population demography, habitat quality, distribution and use and to improve understanding of threats and increase effectiveness of recovery actions.
Southern Interior Reptile and Amphibian Working Group. 2016. Recovery Plan for the Desert Nightsnake (Hypsiglena chlorophaea) in British Columbia. Province of BC. BC Recovery Strategy (Species at Risk)
Scientific Name: Hypsiglena chlorophaea
English Name: Desert Nightsnake
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