Estimates of dispersal and home-range fidelity in American black bears

Abstract

I examined dispersal, home-range establishment, and home-range fidelity in American black bears (Ursus americanus) using radiotelemetry data for individuals whose natal ranges were known (n = 43), individuals whose natal ranges were identified using microsatellite DNA (n = 13), and individuals whose natal ranges were unknown (n = 86). Dispersal was highly male-biased. Nearly all males emigrated 22–62 km from their natal ranges between the ages of 1 and 3 years. Some males continued to float, moving their ranges 15–68 km between successive years. Most males settled into a permanent home range by age 4 years, and all males settled by age 7 years. One 8-year-old male apparently did not disperse and resided only 7 km from his natal range. Females were more philopatric and settled 0–7 km from their natal ranges. Only 1 female moved her range >20 km at the age of 5 years. The adaptive significance of male-biased natal dispersal is discussed.