Population Characteristics of Grizzly Bears in Glacier National Park, Montana

Abstract

Grizzly bears (Ursus arctos) were studied in Glacier National Park, Montana, from 1967Montana, from through 1971. Annual samples of density permitted total park population estimates that ranged from 175 to 230 grizzlies. Mean population composition was 49, 19, 17, and 15 per cent unclassified adults, productive females, cubs, and yearlings, respectively. Production of cubs varied from year to year. Comparable litter sizes for cubs (1.7) and yearlings (1.8) suggested a low mortality rate for cubs. Differences in productivity between years appeared related to variations in length of maternal relationships. Social structure was characterized by a predominance of single individuals and family groups. Other groupings resulted from mating behavior, maintaining the integrity of litters following dissolution of the maternal bond, unusual relationships, or response to preferred food sources. A mean mortality of 1.8 grizzlies per year resulted from management to protect park visitors. Mortality in areas immediately adjacent to the park is summarized. Population regulation and the impact of human activity on the population are discussed.

Den-site characteristics of arctic coastal grizzly bears (Ursus arctos L.) on Richards Island, Northwest Territories, Canada

“…Densities ranged from one bear per 106 square kilometres to one per 175 square kilometres. This density compares well with those in the Brooks Range of northeast Alaska of one bear per 1 19 square kilometres (Quimby 1974) and one per 228 square kilometres (Crook 1971) and these are all low compared with interior mountain grizzly densities of one per 18.1-28.5 square kilometres (Mundy and Flook 1973), 21.2 square kilometres (Martinka 1974), and 22.8-27.2 square kilometres (Pearson 1975).…”

The brown bear in Poland: its history and present numbers

“…The average number of cubs per female in Poland stands at 1.4 -a value which is rather low when compared with corresponding data obtained in North America (Martinka, 1974;Pearson, 1975), and in Northern Europe (Novikov et al, 1969).…”

“…The annual population increments given by other authors ranged, in North America, between 14 to 26% (Mundy & Flook, 1973) or attained 19%, as average for a five-year period (Martinka, 1974). In Slovak Tatra Mts.…”

“…There are diverse opinions about the cub mortality in the first year of life. In contrast to Martinka (1974) and Pearson (1975), Mundy and Flook (1973), Novikov et al (1969), and Randik (1971) point at significant mortality within the first year.…”

Grizzly Bear Density in Glacier National Park, Montana

“…Early (pre-1967) methods used in GNP to estimate grizzly bear population size were informal, often unspecified, and likely unreliable (Baggley 1936). Martinka (1974) estimated population size from density calculations based on annual sightings of unmarked bears in a core area of GNP and extrapolation to the entire park. Because grizzly bear population trends during the 1980s-1990s adjacent to GNP were inconsistent, trends in the park could not be inferred from neighboring areas.…”