Microhabitat Selection of Woody Debris by Dekay's Brownsnake (Storeria dekayi) in a Dune Habitat in Ontario, Canada

Abstract

Understanding habitat selection is a fundamental goal of ecology and is vitally important for effective species conservation. Dekay's Brownsnake (Storeria dekayi; hereafter “Brownsnake”) is one of the most widespread snake species in eastern North America, and its association with cover objects is generally well known, but details regarding choice of refuges are largely unknown. We investigated Dekay's Brownsnake microhabitat use during annual surveys at Point Pelee National Park, Ontario, Canada from 1990 to 2010. We systematically checked all woody debris in stabilized dune habitat for snakes and noted the size and state of decay of woody debris that was used. Nearly all of our observations were of gravid females under woody debris. Greater use of large, moderately decayed woody debris relative to the range of available debris provided strong evidence of selection. Although most snakes observed were solitary, we found a significant number of aggregations. Female Brownsnakes appear to migrate to stabilized dune from other habitats in the park to select suitable woody debris for gestation and parturition. Although these refuge sites would reduce predation risk, they also provide a moister and cooler microclimate than ambient conditions. Numerous observations of shed skins also suggested that this woody debris provides important microhabitat for ecdysis. Analysis of relative abundance over time showed considerable variation in numbers (1–31/yr) and an increasing trend. Our results provide strong evidence of microhabitat selection by this species and highlight the importance of not making generalizations about microhabitat requirements, even for common snake species.