Maternal effect and interactions with philopatry in subadult female American black bear, Ursus americanus, den selection

The selection of suitable locations to fulfil life history requisites is an important process that can influence the survival and development of individuals and the persistence of populations. The impacts of site selection are well documented across taxa, but the driving forces behind site selection, especially regarding transgenerational behaviour, are less well understood. Philopatry (the tendency for an individual to remain near its natal home range) and maternal effect (a nongenetic transfer of phenotypes from mother to offspring) are two factors often thought to influence birth site selection behaviours. We investigated black bear, Ursus americanus, transgenerational den type selection behaviour by analysing a long-term data set containing den selection data of 168 2-year-old subadult females during 1984-2013 at four study sites in Maine, U.S.A. to determine whether there is evidence of philopatry and maternal effect on den type selection. Using logistic regression and model selection, we found evidence that both mechanisms play a role in subadult den type selection. Bears that spent the last winter with their mother in a high-protection den were more likely to select that den type as a subadult. Furthermore, in instances of differences in transgenerational den type selection, most subadults (79%) transitioned from a yearling den of lower protection to a subadult den of higher protection. Transitional behaviour might indicate that subadult black bears also account for environmental plasticity and mediate their den selection accordingly, without the benefit of prior independent denning experience. Future research should evaluate the relationship between den type and offspring recruitment to examine whether an individual-level maternal effect is manifested at the population level. Our results suggest that behavioural maternal effects, in part, influence transgenerational den type selection in black bears, and by extension may influence the behavioural phenotypes of other species with extended periods of maternal care.