Patch and matrix level influences on forest birds at the rural–urban interface

Abstract

Urbanization has altered many landscapes around the world and created novel contexts and interactions, such as the rural–urban interface. We sought to address how a forest patch’s location in the rural–urban interface influences which avian species choose to occur within the patch. We predicted a negative relationship between forest bird richness and urbanization surrounding the patch, but that it would be ameliorated by the area of tree cover in the patch and matrix, and that total tree-cover area would be more influential on forest bird species richness than area of tree cover in the focal patch alone. We conducted bird surveys in 44 forest patches over 2 years in Southeast Michigan and evaluated bird presence and richness relative to patch and matrix tree cover and development density. We observed 43 species, comprised of 21 Neotropical migrants, 19 residents, and three short-distance migrants. Focal-patch tree-cover area and the matrix tree-cover area were the predominant contributors to a site’s overall forest-bird species richness at the rural–urban interface, but the addition of percent of over-story vegetation and percentage of deciduous tree cover influenced the ability of the patches to support forest species, especially Neotropical migrants. Development intensity in the matrix was unrelated to species richness and only had an effect in four species models. Although small forest patches remain an important conservation strategy in developed environments, the influence of matrix tree cover suggests that landscape design decisions in surrounding matrix can contribute conservation value at the rural–urban interface.