Denning Characteristics of Black Bears in the San Gabriel Mountains of Southern California

Abstract

Denning habits of San Gabriel Mountain black bears were studied <br /><br />during the winters of 1987 through 1990. Mean denning period of five male bears <br /><br />was mid-November to mid-March. Denning periods for all bears ranged from <br /><br />late October to late March. Bears entered dens significantly later in 1988 than in <br /><br />1987, 1989, and 1990 (P < .05). We speculate that fluctuations in food item <br /><br />availability might have affected the onset of denning. Exit dates (x 2 = 1.2, P = <br /><br />0.758) and denning duration (x 2 = 4.79, P — 0.1 87) were not significantly different <br /><br />between years. Dens were located primarily in tree cavities {Pseudotsuga macro- <br /><br />carpa and Quercus chrysolepis) or under large boulders. All bears with more than <br /><br />one known den site reused a previous den. No incidents of winter activity were <br /><br />observed.