INFLUENCE OF FIRE AND JUNIPER ENCROACHMENT ON BIRDS IN HIGH-ELEVATION SAGEBRUSH STEPPE

Abstract

Abstract We examined relationships between high-elevation sagebrush (Artemisia spp.) steppe habitats altered by prescribed fire and western juniper (Juniperus occidentalis) encroachment on breeding distributions of Brewer's Sparrows (Spizella breweri), Vesper Sparrows (Pooecetes gramineus), Green-tailed Towhees (Pipilo chlorurus), and Sage Thrashers (Oreoscoptes montanus) on Steens Mountain in southeastern Oregon. In 2000 we conducted fixed-radius point count surveys at 172 sites encompassing burned and unburned sagebrush habitat and a range of juniper densities. For each bird species we developed habitat models using local variables measured in the field and landscape variables derived from remotely sensed data. Akaike's Information Criterion (AICc) was used to select the best-approximating model from a suite of a priori candidate models. Brewer's Sparrows, Sage Thrashers, and Green-tailed Towhees were positively related to increasing local sagebrush cover or percent sagebrush in the landscape, whereas V...