Developing on my earlier work (Stringham 1980) and that of McCullough (1981), influences of adult male abundance on rates of reproduction and subsequent attrition (mortality + net emigration) were evaluated for grizzly bears (Ursus arctos) by analysis of the data of Craighead et al. from Yellowstone National Park 1959-70. Years when adult males were most abundant were also those in which (1) the litters conceived were smallest when censused at median age 0.5 year postpartum, and (2) the cohorts born were comprised of fewest litters at that age. Cohorts produced during years of peak adult male abundance were not only smallest at age 0.5, but showed the highest rates of attrition to at least age 2.5 years. Apparently adult male abundance and/or some closely linked factor, perhaps availability of food, governed not only abundance but quality of infants, which in turn governed survivorship and competitive ability for space and resources in Yellowstone National Park to age 2.5. That coincides generally with relationships between rates of reproduction and of attrition vs. abundances of adult males and of food observed by Rogers (1976, 1977) for black bear in Minnesota. McCullough (1981) reached some of these same conclusions.
- Volume 5
- Issue
- Pages 140-151
- Publication Date 1 January 1983
- DOI 10.2307/3872531
- File Size 490.99 KB
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