Snake occurrences in grassland associated with road versus forest edges

Roads cause direct mortality of animals, but less is known about how this mortality translates into changes in populations. This is particularly true for snakes, which have been subject to little research at the population level compared to other taxa. We studied the effects of proximity to a heavily traveled road on snake populations in three old-field sites at Cicero Swamp Wildlife Management Area in Cicero, New York. We conducted 26 surveys of snakes from June to August 2006 on a regular grid of cover boards at different distances from the road and nearest forest edge and measured the microclimate at each cover board. Adult Common Gartersnakes, Thamnophis sirtalis, and Northern Brown Snakes, Storeria dekayi dekayi, occurred independently of distance from the road but were more abundant farther from the forest edge. The lack of a "road effect" was surprising, given that both species of snakes have been shown to be prone to road-mortality in previous studies and could be caused by either snakes avoiding crossing roads or mortality events being rare. Increased abundance of snakes farther from the forest edge suggests that snakes prefer sites that receive direct sunlight for longer periods of the day. Our study indicates that snake abundance is not necessarily influenced by proximity to roads and that the location of other habitat edges such as a forest-grassland interface may be a more important driver of patterns of spatial distribution.