Summary

Urban areas are expanding and intensifying worldwide, which modifies wildlife habitat; native vegetation is replaced by structures, roads, and other urban features. Although many species of wildlife inhabit and thrive in urban environments, the density of bird species appears to be highly responsive to land cover alteration, in addition to being reduced in cities relative to surrounding areas. However, the effects of urbanization on biodiversity are only minimally documented. Long-term datasets reporting temporal changes in species composition and species gains and/or losses are required. In fact, many urbanization studies substitute time for space in an attempt to document the impacts of urbanization through time.

Over the past half-century, the greater Phoenix metropolitan area has been one of the fastest-growing regions in the US, experiencing rapid urban expansion in addition to urban intensification. This backdrop provides an ideal setting to monitor biodiversity changes in response to urbanization, and CAP LTER has been using a standardized point-count protocol to monitor the bird population in the greater Phoenix metropolitan area and surrounding Sonoran Desert region since 2000. The point count locations span a diversity of habitats including urban, suburban, rural, industrial areas, parks, agricultural fields and the native Sonoran Desert. Many monitoring locations are co-located with other CAP LTER long-term monitoring programs, such as the Ecological Survey of Central Arizona, ground-dwelling arthropod monitoring and Salt River biodiversity, allowing investigators to leverage data from multiple monitoring efforts. Censuses are conducted in the winter and spring to capture the bird community at the peaks of activity, and each birding location is visited by three different professional birders each season to identify all birds seen and heard in the sampling radius.