Re-estimating the Size of the Polar Bear Population in Western Hudson Bay


  • N.J. Lunn
  • I. Stirling
  • D. Andriashek
  • G.B. Kolenosky



population estimates, population models, polar bear, Ursus maritimus, Manitoba, Ontario


A mark-recapture study of polar bears (Ursus maritimus) ashore during the ice-free period of Hudson Bay was undertaken in 1994 and 1995 to re-estimate the size of the western Hudson Bay population. Previous estimates were based on animals caught between the Churchill and Nelson Rivers; consequently, bears in the southern part of the geographic range of this population were not sampled. We used Jolly-Seber models to re-estimate population size from two data sets: bears handled between the Churchill and Nelson Rivers from 1984 to 1995 and bears handled between Churchill and the Manitoba-Ontario border from 1984 to 1986 and by us in 1994 and 1995. Both data sets gave similar estimates. Thus, our best estimate of the size of the western Hudson Bay polar bear population is 1200 ±250 animals in autumn 1995.