Bed site selection by female North American black bears (Ursus americanus)

Abstract

Abstract Sleep is important for memory consolidation and maintaining metabolic homeostasis, but sleep can expose animals to inclement weather and predators. Consequently, selection of sleeping sites is important. We tested three sets of hypotheses related to selection of bed sites by female American black bears (Ursus americanus) at two study sites. During 2009–2013, we outfitted 14 female black bears west of Ely, Minnesota, with Global Positioning System collars that reported bear locations every 10 min. We visited 101 bed sites, each identified from clusters of estimated locations where a bear was on site for ≥4 h on two or more occasions, and recorded bed characteristics, forest composition, canopy closure, and ground cover. We matched each bed site with a control site where we collected the same data. During 1987–1991, we outfitted three female black bears south of Ely with very high-frequency transmitter collars and walked with the bears to collect detailed behavioral data. We used the written data records to identify 62 bed sites where bears slept ≥2 h and where bed characteristics were documented. We matched each bed site with a control site approximately 6 h different when the bear was active. Of the bed sites, 132 were used during night and 31 during day. The two study areas differed in the amount of lowland habitats. At both sites, female bears chose bed sites disproportionately in lowland sites with high canopy cover and next to a tree, especially a white pine. Female bears with cubs selected upland bed sites more often than did females without cubs and also more often selected sites adjacent to a tree with coarse bark, which cubs could climb easily. Distances to roads and houses did not affect selection of bed sites by females either with or without cubs.