Modeling the relationship between habitat preferences and home-range size: a case study on a large mobile colubrid snake from North America

Effective wildlife conservation plans should consider both the habitat needs and spatial requirements of the species in question. Studies that focus on the correlation between the habitat preferences and movement patterns of wildlife, particularly snakes, are uncommon. We attempted to determine how habitat preferences or quality influenced movement patterns of snakes. To answer this question, we created a case model that incorporated habitat preference or avoidance information rigorously obtained for bullsnakes Pituophis catenifer sayi from 2003 to 2005 at a site in the upper Midwestern US and compared it with minimum convex polygon estimates of home-range size. We employed geographical information systems to model the amount of preferred (open bluff faces) and avoided (agricultural fields and closed canopy forests) habitats within each estimated home range and compared them via multiple linear regression. We also tested the influence of gender, length and weight on home-range size. Our results indicate that home-range size increased primarily as a function of the amount of avoided habitat. This supports the hypothesis that habitat quality has an impact on wildlife movement patterns, and the relationship between habitat needs and spatial requirements should be considered when conserving or managing species.