Black Bear (Ursus americanus) Foraging on Black Cottonwood (Populus trichocarpa) Catkins in Southeast Alaska

Black Bears (Ursus americanus) in southeastern Alaska forage intensively on seed pods and male and female catkins of Black Cottonwood (Populus trichocarpa), often breaking many branches from the trees. We examined the relationship of tree damage to tree size and sex, and to content of selected nutrients in the catkins. Tree damage was related to tree girth: medium-size trees were more heavily damaged than small or large trees, possibly because more branches can easily be reached from a safe perch near the trunk. Overall, female trees were more heavily damaged than males. Foraging intensity was not clearly related to the content of important elements (N, P, K, Ca, C) in catkins and seed pods. Concentrated use of cottonwoods in the study area may occur because high human density offers some protection of small Black Bears from larger bears, and medium-sized cottonwoods are common in this recently deglaciated, early-successional area.