Breeding Biology and Diet of Red-Tailed Hawks in Puerto Rico

Abstract

We studied nonmigratory populations of red-tailed hawks (Buteo jamaicensis jamaicensis) along a gradient of altitude and moisture in Puerto Rico, at the southeastern limit of the species' geographic range. Territories in dry and moist lowland study sites were dominated by pastures, whereas those in our montane rain forest and cloud forest study sites were dominated by closed-canopy forests. Populations in rain and cloud forests lived at higher densities than those in the dry and moist lowlands, but they had a lower reproductive success. Frequent rain and fog reduced flying time of adults and reduced prey delivery rates at rain and cloud forest nests, increasing nestling mortality. Peak fledging occurred at the beginning of the rainy season and coincided with peak abundance of prey species. The diet of lowland hawks was comprised mostly of mammals, whereas that of hawks in rain and cloud forests was comprised mostly of birds, reptiles, and amphibians captured in the canopy. Rain and cloud forest hawks lived at higher densities than red-tailed hawks in continental North America. The breeding season in Puerto Rico extended from November to August and lasted longer than those reported for other populations of red-tailed hawks. Clutch size and incubation and nestling periods were similar to those reported for continental North America, but fledglings remained in their parents' territories for more prolonged periods in Puerto Rico.