Spatial ecology and multi-scale habitat selection of the Copperhead (Agkistrodon contortrix) in a managed forest landscape
We evaluated the spatial ecology and habitat use of the Copperhead (Agkistrodon contortrix) in managed, pine-hardwood forests in the William B. Bankhead National Forest, Alabama. We used radiotelemetry to monitor 31 snakes (23 males, 8 females [5 gravid and 3 non-gravid females]) over a period of 3 years (2006–2008). Snakes were tracked for one or more seasons in a series of 18 forest stands composed of 6 treatments (Control, Burn, Light Thin, Heavy Thin, Light Thin with Burn, and Heavy Thin with Burn) replicated three times. Home-range estimates for male snakes averaged 17.8 ± 2.3 (based on Utilization Distributions [UD]) and 12.0 ± 1.9 ha (based on 100% Minimum Convex Polygons [MCP]), whereas home-range estimates for gravid female snakes averaged 7.1 ± 1.8 ha (based on UD) and 4.1 ± 1.1 ha (based on MCP) and were significantly different between both sexes for all home-range analyses. We did not detect an effect of forest management on home-range size of male snakes. Macrohabitat use differed among male and gravid female snakes, where male snakes used edge (field and secondary road edges) and Southern Pine Beetle macrohabitats in significantly greater proportion than what was available. Gravid female snakes did not use macrohabitats differently than what was available, but tended to use thinned stands and forest stand canopy gaps for parturition sites. Microhabitat use patterns were similar between male and gravid female snakes, where both sexes tended to use microhabitat sites with relatively greater litter depth and coarse woody debris percent cover compared to random microhabitat sites. Microhabitat use patterns for male snakes tended to differ based on forest management treatment (Thin and Thin with Burn versus Control and Burn stands), where selected microhabitat sites had lower ambient and soil temperatures compared to random sites in thinned stands. Collectively, we illustrated that male A. contortrix displayed hierarchical habitat use, whereas female A. contortrix displayed preference for habitat features at the microhabitat scale only. Overall, our short-term study provides evidence that recently-thinned pine-hardwood stands are not initially used at a frequency greater than their availability, which suggests that microhabitat and microclimate conditions likely limit use immediately following management.