IMPACTS OF SUPPLEMENTAL FEEDING ON THE NUTRITIONAL ECOLOGY OF BLACK BEARS

Black bear (Ursus americanus) damage to managed conifer stands during the spring in the U.S. Pacific Northwest is a continuing management concern. Because bear damage to managed conifers may reflect the limited availability of nutritious foods, supplemental feeding has been used to decrease damage. Highly palatable, pelleted feed is provided ad libitum from April until late June when berries ripen and such damage stops. We examined black bear use of supplemental feed during the spring and summer of 1998 and 1999 in western Washington. Bears were captured in areas where supplemental feed was provided and in control areas where no effort to reduce conifer damage occurred. Mass gains for bears captured twice were 153 ± 119 g/day (x̅ ± S D) in the fed areas and 12 ± 104 g/day in non-fed areas. Fat gain for bears in the fed areas was 42 ± 50 g/day and 4 ± 59 g/day in the non-fed areas. However, because age-specific body masses and fat content did not differ between the 2 areas, short-term pellet feeding probably has no long-lasting effect on bear condition or productivity. The diet of bears in the fed areas was 55 ± 22% pelleted feed, 7 ± 7% animal matter, and 38 ± 18% vegetation. The diet of bears in the non-fed areas was 13 ± 17% animal matter and 87 ±17% vegetation. Grass and sedge composed the majority of vegetation consumed in both areas. The energy content of Douglas-fir (Pseudotsuga menziesii) and western hemlock (Tsuga heterophylla) sapwood was more digestible (6047%) than grasses and forbs (1 847%). Smaller bears (adult females and subadult males and females) may do most of the damage because sapwood harvesting rates minimize nutritional gain to larger adult males