Relationship Between Testosterone and Movement Patterns in Male Asian Black Bear (Ursus thibetanus)

In male mammals, reproduction and reproductive behavior are strongly influenced by testosterone. While some species exhibit roaming behavior to encounter receptive females and show consorting behavior with females, the relationship between sex hormone and those behaviors remains unclear. To clarify testosterone's influence on behavior, we examined fecal testosterone metabolites (FTM) and behaviors in male Asian black bears (Ursus thibetanus) using collars equipped with GPS transmitters, activity sensors, and animal-borne cameras. We assessed four behavioral variables (daily movement speed, net movement distance, turning angle, activity level) and mating behavior in five males over a cumulative 8 years. Fresh fecal samples, collected at GPS locations of collared individuals, were analyzed for FTM. In total, 111 feces were collected in 2022-2023 across 58 locations. The FTM values and the four behavioral variables were compared between the breeding (May-July) and post-breeding season (August-November) using the Brunner-Munzel test. Overall, FTM were higher, while movement speed and activity levels were lower during the breeding season than in the post-breeding season. These results suggest that some males may engage in consorting associated with elevated testosterone. We further examined the relationships between FTM and the four behavioral variables using Spearman's correlation tests. The correlation between FTM and behaviors varied among males. For example, the relationship between FTM and net movement distance was negative in two males but positive in three males. These interindividual differences in testosterone-behavior correlations were possibly the result of incomplete sampling during mating and consorting, as well as variation in breeding strategies. The negative relationships may indicate mate guarding or consorting, whereas positive relationships may reflect roaming. Our results suggested that the behavior of male Asian black bears may be influenced by increased testosterone, and monitoring testosterone allows us to gain insights into male bear behavior.