Impacts of supplemental feeding on the nutritional ecology of black bears

Black bear (Ursus americanus) damage to managed conifer stands during the s pring in the U.S. Pacific Northwest is a continuing management concern. Bec ause bear damage to managed conifers may reflect the limited availability o f nutritious foods, supplemental feeding has been used to decrease damage. Highly palatable, pelleted feed is provided ad libitum from April until lat e June when berries ripen and such damage stops. We examined black hear use of supplemental feed during the spring and summer of 1998 and 1999 in west ern Washington. Bears were captured in areas where supplemental feed was pr ovided and in control areas where no effort to reduce conifer damage occurr ed. Mass gains for bears captured twice were 153 +/- 119 g/day ((x) over ba r +/- SD) in the fed areas and 12 +/- 104 g/day in non-fed areas. Fat gain For bears in the fed areas cpas 42 +/- 50 g/day and 4 +/- 59 g/day in the n on-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 major ity of vegetation consumed in both areas. Tbe energy content of Douglas-fir (Pseudotsuga menziesii) and western hemlock (Tsuga heterophylla) sapwood w as more digestible (60-67%) than grasses and forbs (18-47%). Smaller bears (adult females and subadult males and females) may do must of the damage be cause sapwood harvesting rates minimize nutritional gain to larger adult ma les.