Black Bear Food Habits in Yosemite National Park

A 5-year study of black bears (Ursus americanus) in Yosemite National Park commenced in 1974 to provide park managers with information necessary for professional stewardship of the species. At the time, both the public and the National Park Service were concerned about increasing property damage and personal injuries caused by bears, and that actions by visi? tors and park staff were inimical to a wild, healthy bear population. Black bear food habits were investigated to determine the role of food of human origin in bear diet. We found that plants comprised 75% of the diet of Yosemite black bears. Herbage, including grasses, sedges, and herbaceous dicots, was the principai food during spring and early summer. Nuts and berries, expecially manzanita (Arctostaphylos spp.) and oak acorns (Quercus spp.) predominated in the late summer and fall. Insects, es? pecially ants (Formicidae), and deer (Odocoileus hemionus) were the principai animal foods. Foods of human origin constituted 15% of the bear diet. Great annual fluctuations in the proportions of the major food categories reflected varying weather pat? terns and efforts by the Park Service to eliminate human foods from black bear diets. Int. Conf. Bear Res. and Manage. 5:1-10 Bears hold a special place in the imagination of the American public, for they are the largest predatory animals most people will ever see free of confinement. American black bears are in many ways the quintessential park animal. Al? though they still occur throughout most of the forested regions of North America (Cowan 1972), they are by virtue of their ecology, ethology, and status as popular rifle targets secretive animals rarely seen. In national parks, however, black bears have adapted to their protected status and the rich food resources that accompany park visitors by becoming bold marauders. The sight or sound of a 100 to 200 kg beast poking around one's camp in the gloom of night has provided a thrill tinged with varying degrees of terror to gen? erations of tourists. The price exacted for this event is often a ruined tent, backpack, or food cooler, a damaged automobile, or occasionally an injury. Prior to World War II, some western national parks, including Yosemite, sought to provide visi? tors a spectacle with a minimum of risk by feed? ing bears garbage at official sites, complete with ranger talks and bleacher seating. Some parks, notably Great Smoky Mountains and Yellow? stone, also developed traditions of tourists intentionally feeding bears. Thus the dark and power? ful marauder acquired another side, the begging 1 Present address: Sequoia and Kings Canyon National Parks, Three Rivers, CA 93271. 2 Present address: Museum of Vertebrate Zoology, Univer? sity of California, Berkeley, CA 94720. buffoon. The sight of 10 bears crowded unnaturally together to feed on garbage, or one standing on its hind legs to reach a proffered morsel, add? ed to the confusion in the public's eye as to just what a black bear really was. In 1963, the report of the Special Advisory Board on Wildlife Management in the National Parks to Secretary of the Interior Stewart Udall (Leopold et al. 1963) set a new direction to Na? tional Park Service wildlife policy by stressing sci? entific management based on research. Yosemite National Park, which had long ago abolished intentional feeding either by staff or visitors, and which had closed its last dumps to bears in 1971, initi ted in 1973 its first explicit "Human? Bear Ma agement Program," and simultaneously con? tracted with the University of California for re? search intended to provide ecological data neces? sary for professional management of black bears. The field work for this study was conducted from 1974 through 1978, a period when bear "incidents" ? property damage or personal injury? were sharply on the rise, and when cap? tures and relocations by the Yosemite Division of Resources Management rose to record levels (Harms 1977). Also during the study period all garbage cans in the Park were bear-proofed, and a visitor education campaign was instituted and intensified to secure proper storage of food. Our study of black bear food habits was one el? ement of a project that sought to obtain basic in? formation as well about population dynamics, physical characteristics, and home range, and to This content downloaded from 207.46. 13.25 on Mon, 12 Sep 2016 04:17:21 UTC All use subject to http://about.jstor. org/terms YOSEMITE BLACK BEAR FOOD HABITS ? Graber and White detect ? if possible ? what effects Park visitors and management activities were having on bear ecology. This study was funded by the National Park Service through a cooperative agreement with the University of California, Berkeley, Department of Forestry and Resource Management. We are grateful to Jan van Wagtendonk for his support, and to the many other staff members of Yose? mite National Park who gave generously of their time. Audrey Goldsmith, Robert Hare, Tina Hargis, Kurt Nelson, and Howard Quigley pro? vided excellent field and laboratory assistance.