Productivity and nest-site selection of a breeding raptor community in South Texas

Despite the diversity and abundance of raptor species found in south Texas, basic ecological information for these populations remains largely unknown. Therefore, objectives of this study were to measure reproductive output and success, as well as to characterize the respective nest sites of members of a breeding raptor community in the Coastal Sand Plains region of south Texas. This report includes new information for populations of the widely distributed great-homed owl (Bubo virginianus) and red-tailed hawk (Buteo jamaicensis), which have not been studied in Texas. Other results will greatly expand our knowledge of those species that have attracted far less research attention, including the crested caracara (Caracara cheriway), white-tailed hawk (Buteo albicaudatus ), and to a lesser extent, the Harris's hawk (Parabuteo unicinctus ). Breeding productivity and success of the red-tailed hawk, white-tailed hawk, and Harris's hawk appeared to be depressed mostly by nest predators, including the great-horned owl and raccoon (Procyon lotor), possibly due to their relatively open nests, compared to crested caracara nests that were constructed deep within densely-branched, thorny shrubs. Among other variables, differences in the height of nest trees and the amount of woody-plant cover distinguished the respective nest sites of the red-tailed hawk, white-tailed hawk, and crested caracara.