Factors influencing breeding ferruginous hawks (Buteo regalis) in the Uintah Basin, Utah

I investigated the reasons for the decline in the local ferruginous hawk (Buteo regalis) breeding population on land managed by the Bureau of Land Management in the Uintah Basin, Utah, by examining what factors influence home-range selection, nest-site selection, and reproductive success. The Uintah Basin is undergoing rapid oil and gas development, and there is concern that this development might be causing the decline.;Assessing the influence of prey abundance on site selection and reproductive success required obtaining abundance estimates for white-tailed prairie dogs (Cynomys leucurus). Because the more common techniques for indexing the size of prairie dog populations require too much time and labor to complete over large areas, I investigated whether a line-transect sampling method or an abbreviated version of the burrow activity method---two less demanding estimation techniques---provided a more reliable relative index of white-tailed prairie dog abundance for ferruginous hawks.;I found active nest sites were associated with higher numbers of active oil and gas wells and smaller distances to the closest active well, but higher levels of reproductive success were associated with larger distances to the closest active well. Thus, although oil and gas development does not appear to have a negative influence on the suitability of breeding habitat, development may have a negative influence on reproductive success if active wells are placed too close to nest sites. The abridged burrow activity method provided a more reliable estimate of white-tailed prairie dog abundance for ferruginous hawks than the line-transect sampling method.;The primary problem for breeding ferruginous hawks in the Uintah Basin appears to be predation. Avian predation was the primary cause of juvenile mortalities and may have resulted from increased competition among avian predators for scarce prey resources, or from increased utilization of juvenile ferruginous hawks as an alternative prey source by Golden Eagles (Aquila chrysaetos ) in years of very low lagomorph abundance.;I provided management recommendations for mitigating the effects of continued oil and gas development on the local breeding population of ferruginous hawks. These findings should help managers improve ferruginous hawk breeding habitat and reproductive success.