Ecology and conservation of prairie rattlesnakes (Crotalus viridis viridis) in relation to movement in a fragmented urban environment

Eighteen prairie rattlesnakes (Crotalus viridis viridis) were tracked using radio-telemetry and 82 snakes were PIT-tagged over a 2-year period in Lethbridge, AB to determine population size, movement patterns, and habitat utilization, and to predict fragmentation effects on the species within an urban locale. Population size was estimated using closed population models at 374 snakes (295 adults) and open population models at 204 snakes (161 adults), greater than an estimate of <50 adults in 2003 (Ernst, 2003) and 2006 (Ernst & Quinlan, 2006). Mean home range sizes, based on 95% minimum convex polygon analysis, differed significantly between years (31.51 ha in 2005, 3.72 ha in 2006). Calculated movement parameters, such as mean distance moved per day, total distance moved over the course of the active season, and frequency of movement varied between years and individuals. Greater-than-expected (under hypotheses of even habitat choice) utilization was observed in habitat types located within coulee and flood plain areas, with apparent preference towards unbroken parcels of grassland or cottonwoods, whereas less-than-predicted utilization of agricultural habitat type was observed. Fragmentation effects on prairie rattlesnake movement and occurrence were examined through modeling and were found to coincide with observed species’ locations, suggesting that prairie rattlesnakes are undergoing modification of movement patterns to avoid highly concentrated human density or use. Influence of weather on the use of vegetative ground cover was observed, as it was accessed more by prairie rattlesnakes at higher temperatures. Recommendations towards future management of the prairie rattlesnake population in Lethbridge are given, including protection of the Bridge View Drive site and inclusion of varied habitat types and terrain when planning habitat and wildlife corridors. Management decisions that ensure remaining habitat parcels and connective areas near rattlesnake foraging or movement corridors are also advocated. Identification of future research focuses include studies on juvenile survivorship, genetic structure, and vehicle-related mortality.

Authors

• Andrus, Wonnita
• University of Lethbridge. Faculty of Arts and Science

• Prairie rattlesnake -- Habitat -- Conservation -- Alberta -- Lethbridge
• Prairie rattlesnake -- Home range -- Research -- Alberta -- Lethbridge
• Prairie rattlesnake -- Radio tracking -- Alberta -- Lethbridge
• Prairie rattlesnake -- Effect of habitat modification on -- Research -- Alberta -- Lethbridge
• Prairie rattlesnake -- Research -- Alberta -- Lethbridge
• Fragmented landscapes -- Research -- Alberta -- Lethbridge
• Dissertations, Academic

Identifier

hdl:10133/2620

OAI identifier oai:identifier

oai:opus.uleth.ca:10133/2620