Meeting Abstract

7.5  Jan. 4  Effects of habitat, age, and sex on black bear carnivory: a stable isotope approach HATCH, K.H.**; ROEDER, B.L.; AUGER, J.; BLACK, H.L.; BUNNELL, K.D.; Brigham Young University; Brigham Young University; Brigham Young University; Brigham Young University; Utah Division of Wildlife Resources khatch@byu.edu

Black bears (Ursus americanus) occupy diverse habitats in Utah, from alpine habitats, to montane forests, to mountain brush (including sage) in semiarid country. Bears are long-lived mammals, and in Utah old bears (10+ years) are relatively common, partly because hunting pressure is relatively light throughout the state. These conditions allowed us to ask how habitat, age, and sex affects carnivory in black bears. Visual observation of bears is time consuming and costly, and analysis of bear scats underestimates carnivory because meat is highly digestible; therefore, we analyzed ¹⁵N/¹⁴N ratios in the hairs of bears as a measure of their carnivory. Hairs, a vestigial premolar (for age determination by cementum annuli analysis), sex data, and location data were gathered from hunter-harvested bears checked at Utah Division of Wildlife offices in 2005. Our analysis showed that male black bears in Utah are more carnivorous than female black bears by approximately one-third of a trophic level. Carnivory increased with age for some hunt units within Utah, but not all. Finally, the ranges of the most carnivorous bears coincided with those parts of Utah where sheep are grazed, suggesting that these bears may utilize sheep as prey or carrion.