Breeding Raptor Census in Grand Teton National Park, 2002

Abstract

We documented abundance and diversity of raptors in a relatively undisturbed landscape in Grand Teton National Park, Wyoming, from February through August 2002. Within a 31.1 km2 study area we located 46 nesting pairs that consisted of 9 raptor species. The American kestrel (Falco sparverius) and the Common raven (Corvus corax) were the two most abundant species on the study area. We considered Common ravens as an ecological and trophic level equivalent of raptors. Six of nine species fledged at least one young, and the mean number of young fledged per occupied nest for all species was 1.0 (sd = 1.0, range = 0 to 3.0). We observed complete nesting failure for Swainson's hawks (n=4 nests), Bald eagle (n=1 nest), and the Long-eared owl (n = 1 nest). We located the territory but not a nest for two Great horned owl (Bubo virginianus) adults, and two Sharp-shinned hawk adults. Six of the nine species observed in 2002 migrate, and two of the nine species are known neotropical migrants. Cold and wet weather conditions along with a high wind storm during the early incubation period appeared to have a negative effect on the breeding success of stick-nest breeders on the study area.