Snakes in fragmenting landscapes
Andrews, Kimberly Marie
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Development and habitat loss pose the most serious threats to reptile persistence. The overall objective of this study was to provide initial assessments of snake behaviors around landscape fragmentation features, in particular the initial stages of residential and recreational development and roads. I used data from three studies in South Carolina to examine: 1) the variation within and among snake species recorded on roads using a 50-year database; 2) home range and spatial use patterns of timber rattlesnakes (Crotalus horridus) in a developing coastal landscape; and 3) variation in overwintering ecology among populations of C. horridus. In an investigation of road captures, 15 of 29 species exhibited male-biased road captures. I also noted that longer and heavier individuals were more susceptible to road mortality. Secondly, I analyzed home range sizes for C. horridus using multiple home range estimators (minimum convex polygons (MCP), fixed kernel distributions, and LoCoH nearest neighbor convex hulls (NNCH)). Males exhibited larger home ranges than females. Home ranges in developing areas were significantly larger than in undeveloped areas for MCPs and 95% fixed kernel estimations. The NNCH analyses revealed that snakes were not necessarily using more space in developed areas, but that ranges were more sprawling and fragmented. Sex influenced the size of breeding and foraging areas, but development only affected foraging ranges. Lastly, I assessed variation in winter surface activity, number of hibernacula used, body posture, and hibernacula structure types between a coastal and an inland population of C. horridus at different temporal scales. At seasonal and monthly scales, average air temperature and snake body condition significantly influenced surface activity and the number of hibernacula used. Average temperatures were significant in individual daily models, and precipitation and photoperiod also accounted for some of the variation. Coastal and inland sites were significantly different in terms of dominant hibernacula and structure types used during the winter. This assessment of initial landscape development is important to understanding the process of urbanization and wildlife population declines. These data facilitate the production of wildlife conservation plans for developing landscapes.