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Journal Publications
McLoughlin, P.D., H.D. Cluff, R.J. Gau,
R. Mulders, R.L. Case, and F. Messier. 2002. Population delineation of
barren-ground grizzly bears in the central Arctic. Wildlife Society
Bulletin 30:728-737.
Abstract
We identified spatially distinct
populations of barren-ground grizzly bears (Ursus arctos) in a
235,000 km2 study area northeast of Yellowknife, Northwest
Territories, Canada. We tested for the presence of population clusters of
bears using movement data obtained from satellite telemetry (n=55
female bear-years, n=42 male bear-years) and multivariate cluster
analysis. We identified geographic range of female and male population
clusters using the fixed-kernel range estimator with least-squared
cross-validating to determine bandwidths, and defined population unit
boundaries by referring to the 70% contours of population ranges. To
validate population units, we required spatial clusters for female and male
bears to be similar so distinctive female and male components could be
contained within common population boundaries. Further, we needed
population growth rates to be a result of intrinsic birth and death rates
and not immigration or emigration rates. Thus, no more than 1 radiotracked
animal of either sex (between 2.1% and 4.3% of a given population unit
sample) could immigrate to or emigrate from an identified population unit
annually. We obtained independent clustering solutions that grouped both
female and male grizzly bears into 3 area: the North Slave region, Bathurst
Inlet region, and Kugluktuk region. Although female population ranges at
the 70% contour level were completely contained within established
population unit boundaries, male population ranges demonstrated overlap.
Annual exchange rates were high (3.4-13% for females, 7-35% for males) among
the 3 populations. Bears in our study area should thus be managed as an
open (continuous) population. |
