Great Basin Naturalist


During the summer of 1969 a survey involving 45 nesting nocturnal and diurnal birds of prey was made. Prey items, nest site selections, and productivity for great horned, long-eared, burrowing and short-eared owls, golden eagle, prairie falcon, kestrel, harrier and ferruginous, red-tailed and Swainson's hawks were determined. The turkey vulture, accipiter hawks, barn and screech owls were also recorded. The total raptor impact on the environment was determined to be slight, whereas the limits placed on the nesting species are considered substantial. It was noted that immature eagles were in the valley and, because they did not require a nest site, were able to utilize areas away from suitable nest sites. Ferruginous hawks had a clumped distribution because the nest sites (junipers) were aggregated on the valley floor. Red-tailed hawks and kestrels required nest sites not typically found in undisturbed desert communities and were found more commonly in agricultural lands. The golden eagle was the only species studied that did not produce a replacement population, i.e., a minimum of two young per pair, although observations outside the valley proved this to be a local phenomenon.