Survival and antipredator behavior of woodchucks (Marmota monax) along an urban-agricultural gradient

Understanding effects of urbanization on biodiversity requires integrated assessments of demographic and behavioral responses by species, including urban-adapter species. Past research on mammalian responses to urbanization has emphasized predators, but prey species could respond to additional factors including variation in predation risk. We examined spatial heterogeneity in real and perceived risk across an urbanization gradient by comparing survival rates, causes of mortality, and antipredator behavior of adult woodchucks (Marmota monax (L., 1758)) within an agricultural landscape in Illinois from 2007 to 2009. Survival rates were higher, and effects of urbanization were stronger, during the inactive season. Rural woodchucks primarily died from predation or costs associated with hibernation, whereas urban woodchucks mainly died from vehicle collisions or unknown reasons. Mean levels of antipredator behavior were unrelated to urbanization, but among-individual variation in vigilance levels increased in urban areas, which may reflect increased spatial variation in disturbance levels within urban environments. Distances from burrows while foraging and flight initiation distances also were unrelated to urbanization, suggesting that urban woodchucks were not strongly habituated to humans. Our research provides insights into demographic and behavioral responses to urbanization, and constraints to responses, by an urban-adapter species.