How scale influences birds' responses to habitat features in urban residential areas

How individual species respond to urbanization depends on both the specific habitat features they require as well as the spatial scale at which they respond to habitat changes. Urban areas represent both a unique challenge and opportunity for the conservation of native avian species because, at smaller scales, the actions of individual homeowners may be critical to maintaining populations of certain species, whereas other species may require broader scale conservation measures. Understanding how scale, land ownership, and habitat features interact in influencing presence of native birds is crucial to developing sound conservation and land use strategies in urban and developing areas. We studied the relationships between ten native bird species and a suite of human-influenced habitat features at two spatial scales, individual properties and neighborhoods, to determine which factors and scales were most important to each species. At the smaller scale, variables associated with native vegetation were important for eight species, whereas the amount of open space was positively associated with six species at the larger scale. Three species were most strongly associated with habitat features at the individual property scale, and two with features at the neighborhood scale. The remaining five species were influenced by habitat features at both scales, and showed strong cross-scale interactions. Our results suggest that the presence of some native species in urban areas can be influenced by the actions of individual homeowners, whereas the presence of other species will require broader scale approaches involving neighborhood groups and city managers.