Use of Patchy, Early Successional Slope Habitat Along Coastal Sun-Facing Beaches by the Western Fence Lizard Sceloporus occidentalis at the Species' Northern Geographic Extreme

Comparisons among core and peripheral populations of animals for patterns of habitat use may be an important step in an area of ecological research: the quest to understand the mechanisms underlying species range boundaries. My research on the Western Fence Lizard, Sceloporus occidentalis, at the northwestern edge of the species' geographic range, is intended to lay the groundwork for future analyses of peripheral populations. Sceloporus occidentalis is a propitious species for studying peripheral animal populations because (1) relative to dryland habitats more typical of the species nearer the core of its geographic range, the peripheral population resides in a relatively unique beach-edge maritime habitat, and (2) it is found in high local abundance, is easy to observe and capture, and has low vagility relative to birds and mammals. My research addresses the habitat preferences, dispersal tendencies, and spatial distribution among individuals of S. occidentalis in a population at the species geographic extreme in western Washington. In 2013-2014 I captured, measured, and marked 359 lizards on the central beach in an apparent metapopulation along the Washington coast west of Marysville, WA. I recorded detailed habitat characteristics for every 10-meter stretch of beach using the line-intercept method (transect was set perpendicular to beach edge) and used Multidimensional Scaling analysis to correlate habitat characteristics with lizard sighting locations, thereby determining which sections of coastal beach edge were most heavily used by fence lizards. Similarity Percentage (SIMPER) analysis was used to determine which habitat characteristics were associated with most of the difference between occupied and unoccupied habitat areas. These characteristics and their relative influences on habitat differences were: distance to nearest