Seungyun BAEK, Tomoko NAGANUMA, Koji YAMAZAKI, Shinsuke KOIKE

Male reproductive success is generally influenced by how effectively males secure and maintain exclusive access to receptive females. Male body size influences outcomes of male–male competition, whereas mating season home-range size reflects roaming and mate-searching effort. Because direct observations are limited, consortship between males and females (association/guarding) is rarely described in bears. Here, we examined how body size and space use influence consortship frequency and duration in male Asian black bears (Ursus thibetanus), using animal-borne video, activity sensor and GPS.
We defined days with female appearances on video from male bears equipped with GPS collars integrating video cameras and activity sensors as consortship days, and fitted a generalized linear mixed model (GLMM) relating activity proportion obtained from activity sensor to consortship probability. Using this model, we inferred consortship days from activity data of GPS-collared males equipped only with activity sensors, and aggregated consecutive inferred consortship days into events. We then modeled the number and the duration of consortship events with GLMMs including male’s body size and home-range size during the mating season, with event number as a covariate when analyzing duration.
We found that male bears exhibited lower daytime activity proportions during consortship with females. Home-range size was not associated with the number of consortship events, whereas body size increased the number of consortship events and consistently increased their duration. The duration of consortship events declined as their number increased and home-range size increased. Our results suggest that larger males may gain an advantage by accessing females more often or maintaining longer associations, while extensive space use and frequent encounters were associated with reduced maintenance time per event, consistent with a time-allocation trade-off during the mating season.