Home range and male reproductive optimization in black bears

Home ranges and body sizes of males are typically more than twice as big as those of females in polygynous mammal species. The differences in home range size have been hypothesized to result from males' greater energetic requirements, or from males' need for more mates to increase their reproductive success. These hypotheses were investigated for black bears in the southern Appalachian mountains using two approaches: a simulation model of male movements that optimize reproductive success, and an analysis of seasonal changes in home range size and movement rates. Limited evidence from models and empirical measurements indicates that females' yearly energy requirements are close to those of males when the costs of reproduction are included, even where males have much larger body sizes.;Home range sizes were estimated using a non-parametric kernel density estimation technique to determine the utilization distribution. Monte Carlo simulations showed that when the fixed kernel bandwidth was chosen by cross validation, kernel estimates of home range size were more accurate than harmonic mean estimates.;An optimal diet selection model was adapted as a mate choice model. Males' optimal mating success was obtained by courting an encountered female only if she was perceptibly approaching estrus. Males' mating success and movements during the breeding season were predicted by a spatially explicit, individual-based model. Maximal reproductive success resulted from home ranges that included between 3 and 7 breeding females. Field data showed that adult males' home ranges during the breeding season would include an average of 4 breeding females.;Radio telemetry location estimates of black bears were used to determine home range sizes and movement rates. Males' yearly home ranges were approximately twice as large as females'. Bears of all sex and age classes had smaller home ranges and lower movement rates in the spring than in the breeding or post-breeding seasons, except adult females, which had larger home ranges and higher movement rates in the spring. Adult males' movement rates were highest in the breeding season and dropped in the post-breeding season, movement rates did not differ between these seasons for any other classes. The large spring home range sizes and movement rates of adult females may be due to the nutritional demands of pregnancy. The large breeding season home range sizes and movement rates of adult males are in agreement with the model of reproductive maximization.