The Western Rattlesnake (Crotalus oreganus) is a large snake (up to 1.3 m long) with a triangular head, narrow neck, vertical pupil, and a tail that ends with a rattle or button. The background body colour is brown, olive, or grey. A series of large dark-brown blotches surrounded by light-coloured borders, or ?halos,? run down the middle of the back, with smaller, similar blotches along the sides. A dark line runs between the eye and the jaw. Juveniles have a lighter background colour with more contrasting blotches on the back. Neonates (newborns) are ~285 mm long and have a ?button? instead of a rattle. Western Rattlesnakes use fangs to inject chemicals that subdue prey and begin digestion. If threatened or harassed, rattlesnakes may use venom for defence, although unprovoked bites on humans are relatively uncommon and human deaths are extremely rare in British Columbia.
Western Rattlesnakes occur in the dry Southern Interior of the province within five geographic areas: Thompson-Nicola, Vernon, Okanagan-Similkameen, Midway, and Grand Forks. They are associated with relatively low-elevation (mostly < 1430 m) rock outcrops, talus, riparian, shrub?steppe, and open ponderosa pine and Interior Douglas-fir forest habitats. Their active season is from March to October.
The Western Rattlesnake was designated as Threatened by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) because of historic and ongoing habitat loss and mortality caused by vehicles and persecution. It is listed as Threatened in Canada on Schedule 1 of the Species at Risk Act. In British Columbia, the Western Rattlesnake is ranked ?S3? (vulnerable) by the Conservation Data Centre and is on the provincial Blue List. The B.C. Conservation Framework ranks the Western Rattlesnake as a priority 2 under goal 2 (prevent species and ecosystems from becoming at risk). Under the provincial Wildlife Act, it is protected from capture and killing. It is also listed as a species that requires special management attention to address the impacts of forest and range activities under the Forest and Range Practices Act and the impacts of oil and gas activities under the Oil and Gas Activities Act on Crown land (as described in the Identified Wildlife Management Strategy). Recovery is considered biologically and technically feasible.
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 persecution. Lower-ranked threats include habitat loss and fragmentation from housing and agricultural development, recreation, fire suppression, and potential diseases from invasive non-native/alien species.
The recovery goal is to maintain or increase the abundance of Western Rattlesnake in each of the five geographic areas in British Columbia and to maintain or increase connectivity within these areas.
The following objectives are necessary to meet the recovery goal and recover the species.
1. Reduce persecution and road mortality to a level that will not affect population viability.
2. Secure den (hibernation) sites and connected gestation, shedding, foraging/migration, and dispersal habitat throughout the species? known range in British Columbia.
3. Address knowledge gaps related to population demography, habitat quality, distribution and use, priority threats and effectiveness of recovery actions.
Southern Interior Reptile and Amphibian Working Group. 2016. Recovery Plan for the Western Rattlesnake (Crotalus oreganus) in British Columbia. Province of BC. Recovery Plan
Topic: Recovery Planning
Scientific Name: Crotalus oreganus
English Name: Western Rattlesnake
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