Movements and survival of fledgling Cooper's Hawks in an urban environment

Cooper's Hawks (Accipiter cooperii) nest in urban and suburban areas across North America, but little is known about movements, habitat use, or survival of fledglings in these settings. We followed 40 radio-tagged, fledgling Cooper's Hawks hatched in Tucson, Arizona in 1999 or 2000, for up to 6 mo to estimate survival, and describe patterns of movement and the environments they use while dispersing. The typical pattern of movement for hawks we tracked through early winter consisted of sedentary behavior in the natal area, followed by relatively long movements beginning 11-13 wk after hatching, and finally sedentary behavior again when they settled into a fall/winter home range. Distances between relocations of individual hawks were, on average, greater for females (x̄ = 6.8 km, range = 0.02-51.7 km, SD = 9.8) than males (x̄ = 3.8 km, range = 0.05-20.8 km, SD = 5.4; t-test, P = 0.02). Home range size for nine hawks during their first fall/winter averaged 771 ha (SD = 403). Distance from center of home range to natal site averaged nearly twice as far for females (x̄ = 10.9 km, range = 4.2-19.5 km, SD = 6.4) as males (x̄ = 6.0 km, range = 2.2-13.3, SD = 5.0), but the difference was not significant (t-test, P = 0.23). Survival of radio-tagged hawks was 67% through 180 d. Hawks used a variety of environments prior to settling for the winter, but were found most frequently (35% of locations) in riparian areas. We found no discernable pattern of habitat selection for land use categories inside winter home ranges. We speculate that the abundance of food may facilitate survival of post-fledging, dispersing hawks in Tucson.