Abstract

Urbanization creates a dense network of paved roads that alters and degrades natural landscapes. Yet, the resulting fragmented terrains still provide essential habitats for a wide variety of urban-adapted taxa. Dekay's Brownsnakes (Storeria dekayi) are urban dwellers that frequently occur at high densities in anthropogenically disturbed environments. However, S. dekayi also exhibit en masse migration during fall, which renders them susceptible to road mortality when migration routes traverse urban road networks. We investigated the fall migration of a S. dekayi population inhabiting an urbanized site along a 2-km road in central New Jersey, USA. Specifically, we characterized S. dekayi road-crossing patterns during the fall migration season and determined environmental factors associated with such patterns. We found high mortality of S. dekayi occurred during their fall migration, with younger individuals and males more prone to road mortality. Roads that are either raised or partially buried and roads close to aquatic habitats were positively associated with number of snake crossings whereas habitats with lawns were negatively related to number of snake crossings. The most important factors that determined the number of road-crossings made by males were raised road topography, which had a negative influence, and the presence of ditches on both sides, which had a positive influence. The main determinant of number of road-crossings made by females was the presence of a forest on one side, which exerted a positive effect. Our work highlights the need to further explore the natural history of urban-adapted common reptiles along with other taxa sharing similar traits to maintain urban biodiversity.