hide You are viewing an archived web page, collected at the request of University of Alberta using Archive-It. This page was captured on 16:33:51 Dec 08, 2010, and is part of the HCF Alberta Online Encyclopedia collection. The information on this web page may be out of date. See All versions of this archived page. Loading media information
Heritage Community Foundation Presents
Alberta Online Encyclopedia
Top Left of Navigation Bar The Nature of Alberta Logo
Species at Risk in AlbertaView our site layout to navigate to specific areasSearch our site for informationObtain help for navigating our sitePlease emails us your questions and comments!View our partners that helped us in this project

Ecosystems OverviewEnvironmental IssuesGeological History of AlbertaAlberta's Natural RegionsAdditional Resources
Visit Alberta Source!
Visit the Heritage Community Foundation
Visit Canada's Digital Collections

Prairie Rattlesnake

Prairie RattlesnakeOf the eight subspecies of the Western Rattlesnake (Crotalus viridis) in North America, the Prairie Rattlesnake, is the only one found in Alberta. The Prairie Rattlesnake varies in distribution and abundance throughout its range. In Alberta, for example, the Prairie Rattlesnake is a "Blue-listed" species, indicating that it may be at risk and susceptible to habitat disturbance, population decline, or reductions in provincial distribution.

The habitat of the Prairie Rattlesnake in Canada has been described as mixed-grass prairie, or as short-grass prairie. Low precipitation, high summer temperatures, and a short growing season characterize the semi-arid climate of the mixed-grass prairie, whereas the short-grass prairie occurs under even drier conditions or intense grazing pressure.

Rattlesnake infront of  denIn Alberta, the Prairie Rattlesnake is found within the Grassland Natural Region, often associated with river and coulee bottoms, badlands, sage flats, and less commonly on open short-grass prairie.  Hibernacula, which allow the Prairie Rattlesnake to survive through long cold winters, are a critical component of Prairie Rattlesnake habitat in northern climates. Slump blocks, meander scarps, subterranean water channels, rock outcrops, and mammal burrows have all been found to provide suitable conditions for hibernacula. Hibernacula are usually found on south-facing slopes which provide maximum solar insulation, while offering protection from prevailing winds. However, a small number of dens appear to be located on, or adjacent to, east- or north-facing slopes. Overwintering dens of the Prairie Rattlesnake are with other species such as Bull Snakes and Garter Snakes.

Rattlesnakes return to their dens each fall, and therefore hunting and basking areas must be available within a reasonable distance from the hibernaculum.  Another potential habitat requirement of the rattlesnake is the presence of a suitable birthing area or rookery where gravid females can aggregate until parturition. Although only a small number of rookeries have been found, these areas have some common features, including the presence of large, flat table rocks overlaying abandoned mammal burrows. It has been suggested that these habitat characteristics provide quick escape from predators as well as appropriate microhabitat for thermoregulation. 

It has been estimated that over two-thirds of the original mixed-grass prairie has been destroyed. This loss, in combination with increased grazing and the construction of roadways and pipelines on the prairies suggest that the availability of suitable habitat for Prairie Rattlesnakes may be declining in the province.

Snake populations in cold climates often develop specific behavioral and physiological strategies for dealing with a shortened active season. In Alberta, Prairie Rattlesnake populations reach the northern limit of their distribution, and restrictions imposed by the colder climate should be reflected in their thermal ecology.

Knowledge of activity patterns in rattlesnakes may also be critical for understanding habitat requirements. During the active season, rattlesnakes may migrate long distances from their overwintering dens.  In the spring, migration appears to be associated with a search for suitable foraging areas. 

Reprinted from Alberta Wildlife Status Report No.  6 (1997), with permission from Alberta Sustainable Resource Development.

Albertasource.ca | Contact Us | Partnerships
            For more on the natural history of Alberta, visit Peel’s Prairie Provinces.
Copyright © Heritage Community Foundation All Rights Reserved