Response of moose calf survival to reduced black bear density : an assessment of the stresses likely affecting the moose population on Hecla Island

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Kotchorek, Raymond E.
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An 18-week (government) black bear translocation program was closely monitored and assessed as to its impact on subsequent moose calf survival rates on Hecla Island, Manitoba in Summer 2000. A total of 12 black bears (or 0.73 bears/10km2) were removed from the island. Alternative timber wolf - white-tailed deer interactions were monitored and big game population estimates were assessed through several different methods. Various human related stresses on moose and land development stresses on moose habitat were also examined and assessed as to their possible impacts on the island's declining moose population. Results from an aerial wildlife survey conducted several months after bear removal indicated a significant increase in the moose calf population. Comparisons of the new moose calf population data with prediction intervals based on regression analyses of past survey data indicated that the calves/100 cows relation realized a significant increase from a pre-treatment ratio of 0:100 to a post-bear removal ratio of 40:100, and the calves/100 adults relation realized a significant increase from a pretreatment ratio of 0:100 to a post-bear removal ratio of 21.4:100. Results from a second (post-study) aerial wildlife survey in Winter 2002 also indicated similar moose calf survival ratios to the 2001 data after three additional bears (or 0.18 bears/10km2) had been removed from the island by Manitoba Conservation Officers in summer 2001. These statistically significant increases in moose calf survivorship relations seem to indicate that the lowered black bear density had an overall positive effect on moose calf survival. An analysis of black bear scats for evidence of moose-calf hair in summer 2000 did not, however, provide a definitive link between black bear predation and moose calf mortality. The continued (short-term) removal of black bears from the island was one of several wildlife management recommendations offered in order to allow for the reestablishment of a viable moose population on Hecla Island. Park and habitat management recommendations are also part of the final output for this study.