Assessment of Peregrine Falcon (Falco peregrinus anatum) Nesting Habitat in the San Francisco Bay Area

Human encroachment into natural environments fragments and degrades the habitat for many species and raptors such as the peregrine falcon (Falco peregrinus) have adapted to the urban environment, co-existing with humans and other wildlife. The habitat preference of the American peregrine falcon subpopulation, F. p. anatum was investigated in the densely urbanized San Francisco Bay Area. In this research, Geographic Information Systems (GIS) applications to evaluate ten environmental attributes and their influence on 47 nesting sites were used. Distances from peregrine falcon nesting sites to two federally listed prey species the California least tern (Sterna antillarum browni) and the western snowy plover (Charadrius nivosus nivosus), respectively, were measured. Analysis of average nearest neighbor distance showed that the spatial distribution of nesting sites was not clustered, but more random (z = -1.56, p = 0.120) indicating that the species was occupying any available territories as they found them. Distance to the two federally listed species differed between the 20-natural and 27-anthropogenic peregrine falcon nest sites (natural = 35.37 km, anthropogenic = 16.30 km, p = 0.001). Analysis revealed the following environmental attributes, elevation, wind, precipitation, and solar radiation, to be of primary importance to the peregrine falcon breeding habitat. These results can be used by managers to assess where peregrine falcons are able to nest and may serve as inputs to a predictive model to forecast potential future nest sites