ESTIMATING GRIZZLY BEAR FOOD-HABITS FROM FECAL ANALYSIS

We fed 27 different food items to captive grizzly bears (Ursus arctos) to investigate the need for correction factors (CF's) when estimating grizzly bear food habits from fecal residue. The amount of food neces sary to produce 1 ml of fecal residue ranged from 0.16 to 40.8 g dry m atter, suggesting that uncorrected fecal analysis are rarely equivalen t to food habits. We propose CF's that relate the volume of residue in the feces to the mass of dry matter ingested. The ranges of these CF' s were 0.16-0.35 for vegetation, 0.51-1.84 for berries, 0.35-1.40 for roots, 0.91-1.25 for insects, 1.54 for pine nuts, 1.54-12.5 for mammal s, and 40.8 for fish. The CF for large mammals depends upon how much s kin, hair, bones, or other poorly digested components are consumed.