Grizzly Bear Reproductive Rate Relative to Body Size
Mean adult body sizes (BS) and reproductive parameters were compared across 12 populations of grizzly bears (Ursus arctos). BS was assessed in terms of mean adult body weight (BW) and skull length (SL). BWs of adult males and females are positively related to each other and to SL. As BS increases, litter size (C/L) and […]
Black Bear Reproductive Rate Relative to Body Weight in Hunted Populations
Litter size, natality (cubs per adult female per year), and maturation rate are positively related to body weights of adult males and females. This is shown by regressions of reproductive parameters on weight, using mean values from each of 7 hunted populations. Maturation rates to weaning and adulthood are, respectively, proportional to the inverses of […]
Fluctuating Asymmetry and Testing Isolation of Montana Grizzly Bear Populations
Fluctuating asymmetry of adult skulls was used to test the genetic isolation of the Yellowstone grizzly bear population from its nearest neighbor. An overall summary statistic was used in addition to 16 other parameters. Tests found the males of the Yellowstone population to be more variable than those of the North Continental Divide Ecosystem. Evidence […]
Precision and Accuracy of Estimating Age of Maine Black Bears by Cementum Annuli
We investigated the precision and accuracy of age estimation by cementum annuli counts for Maine black bears (Ursus americanus). Precision of age estimation was assessed by: 1) a repeated measures analysis of variance design to evaluate effects of reader, reader experience, bear sex, bear age class, and trial; and 2) pair-wise comparisons of estimated years […]
Estimating Grizzly Bear Density in Relation to Development and Exploitation in Northwest Alaska
Grizzly bear (Ursus arctos) densities within a 1,862 km2 study area surrounding a lead/zinc mine in northwest Alaska were estimated using mark-recapture methods during late May and early June 1987. Radio collars were used to mark bears and assess population closure. Density estimates were 1 bear/66 km2 for adults (>3-years-old) and 1 bear/51 km2 for […]
Detection of Differences in Brown Bear Density and Population Composition Caused by Hunting
Liberalized hunting regulations in a portion of southcentral Alaska resulted in an increased sport harvest of brown bears (Ursus arctos). A reduction in population density caused by increased hunter harvest was demonstrated using modified capture-recapture techniques. Density differences were documented between 2 areas of generally equivalent habitats but different patterns of hunter access as well […]
Reproductive Biology of Black Bears in East-Central Ontario
The reproductive characteristics of 241 female black bears (Ursus americanus) ≥3-years-old were examined in east-central Ontario from 1969-1980. During the 12-year period, the percentage of adult females reproducing each year ranged from 13-58 and averaged 38. Litter sizes ranged from 1 to 4 and averaged 1.9 from summer captures and 2.5 from den examinations. Size […]
Sex Weighted Point System Regulates Grizzly Bear Harvest
A system that provided outfitters guiding non-resident hunters with a 3:1 incentive to take male over female grizzly bears was tested in 20 outfitting areas in the Yukon Territory between 1985 and 1988. This system replaced annual quotas, 1980-1984, that had been criticized as being too small, too inflexible, and lacking incentive for male-selective or […]
Population Management of Bears in North America
Population management for black bears (Ursus americanus), brown-grizzly bears (U. arctos) and polar bears (U. maritimus) in North America is reviewed. In different areas bear populations are managed to achieve goals of population control, conservation, or sustained yield. Most North American bears are managed for sustained yields and this topic is emphasized. The consequence of […]
Interactions between Polar Bears and Overwintering Walruses in the Central Canadian High Arctic
There are few records of predation by polar bears (Ursus maritimus) on walruses (Odobenus rosmarus), although their distributions overlap extensively. During the late winter and early spring from 1981 through 1989, we recorded interactions between polar bears and walruses in the central Canadian High Arctic, where walrus movements are severely restricted in the winter by […]
