American black bears (Ursus americanus) require suitable winter den sites to provide security and cover to successfully survive the critical winter denning period. Dens are reused intermittently over decades, if not longer, and may be used by successive bears. On Vancouver Island, winter dens used by black bears have been found in or beneath large diameter (mean of hollow tree dens = 160 cm) trees or structures derived from trees (i.e., logs, root boles and stumps).
Current and historic land management activities in coastal forests have affected the supply of these critical element-level features. Most significantly, forest harvesting has removed many large trees that form these den structures. Furthermore, these large structures are not replaced during forest rotations because the new crops of trees are not allowed to grow to sufficient size for replacement dens to develop. Despite the knowledge that these habitat features are critical to the over-winter survival of black bears, no regulatory protection is in place for these critical structures in BC.
The objectives of this project are two-fold. First, this project aims to attempt to mitigate losses of denning opportunities by enhancing natural structures by creating entrances to cavities in existing old growth trees or large legacy stumps that have hollow centres. Second, this project is evaluating whether bears will use artificial structures specifically designed to compensate for the loss of natural structures. Twenty-one dens (9 in natural structures, 12 in artificial structures) were created in 2014-2015 and were monitored with cameras until 2019. Initial monitoring found bears investigating both types of structures extensively and in 2017-18 and 2018-19 one stump that had been turned into a den (photo above) was used as a den by a black bear! See video (https://www.youtube.com/watch?v=O_dxaZYBC6Q) of creation of den and bear pulling plants inside for bedding. Goals of the project include 1) increased awareness by forest companies of the need for retention of bear den structures and possibilities for den creation in coastal BC, and, 2) increased awareness by government policy makers of the need for regulation to protect these critical forest elements.