Nesting Biology of Urban Cooper’s Hawks in Alameda County, California

In recent decades Cooper’s Hawks have successfully colonized urban landscapes, where there may be ample prey but also a greater prevalence of disease in their prey. We searched for nesting Cooper’s Hawks in and around Berkeley, California, from 2002 to 2010, locating 95 nests, 89 of which successfully fledged at least one nestling. On average, each nest produced 3.6 fledglings. We evaluated the possible effects of the protozoan parasite Trichomonas gallinae on Cooper’s Hawk reproduction from the proportion of potential prey items brought to Lindsay Wildlife Experience that tested positive for the parasitic disease. We did not find a correlation between T. gallinae in potential prey species and nest success (i.e., if the nest fledged any offspring) or reproductive success (i.e., number of fledglings produced). Similarly, we did not find a relationship between reproductive success and distance to parks or percent of impervious surface within 500 m of the nest. The high reported rates of reproduction and high densities of Cooper’s Hawk in Berkeley and neighboring Albany suggest a robust population, and we did not find evidence that T. gallinae influences its reproductive success.