Urban macrostructure and wildlife distributions: Regional planning implications.

Abstract

Urban environments can satisfy the habitat requirements of a variety of wildlife species. It has been shown that urban residents enjoy wildlife near their homes. The goal of this study was to determine if urban wildlife distributions could be predicted by metropolitan planning variables, so that opportunities for urban residents to enjoy wildlife near their homes could be enhanced. Three hundred one random points, stratified into seven zones, based on intensity of urbanization and vegetation type, were chosen in the Tucson metropolitan study area. Birds were censused with the variable circular plot method. Sign of selected mammal species were searched for at a subset of these points. Native bird species diversity declined steadily as housing density increased. The study area still supports a high diversity of native species because of the high levels of natural open space still found intermixed with residential development. The amount of land covered in residential development and the amount of paloverde-saguaro vegetation types with associated riparian areas were the best predictors of native bird species diversity. The data also suggest that plant cover created by man-maintained vegetation is not as attractive to native bird species as naturally occurring vegetation. Ground nesters and insectivores tended to drop out at higher housing densities while seed-eaters were retained. Three patterns of avian response to variables describing the intensity of urbanization and the amount of natural vegetation emerged: urban, suburban, and exurban. Native Sonoran desert birds appear to be highly sensitive to urbanization, as minor increases in residential housing densities lead to declines in diversity. Mammal species appear to be most sensitive to the size of open space areas and fragmentation and isolation of natural lands. Metropolitan planning processes may be limited in their ability to retain high species diversities. The impacts of urbanization on wildlife diversities may be mitigated through sensitive open space planning.