IMPACT OF WOLF AND BLACK BEAR REMOVAL ON COW:CALF RATIO AND MOOSE DENSITY IN SOUTHWESTERN QUÉBEC

Abstract

Over 4 winters, 7 to 13 wolves were removed annually from a study area and a surrounding buffer zone covering together 2150 km² in La Vérendrye Game Reserve. In an adjacent 360-km² block, 25 to 30 black bears were removed every June over 3 consecutive years. Fall estimates indicated that wolf density was reduced to approximately 1 animal 100 km^-2 In the removal area, as compared to 1.5 wolves 100 km^-2 in the control block. Bear density was not estimated but females were severely affected by the removal. Trapping effort (days-trap/capture) for female bears increased from 35 to 109 from the first to the third year, while the mean age dropped from 8.5 to 3.3 years. Male harvest was more stable. Observation of radio-tagged female moose probably under estimated birth rate and calf mortality. Based on January cow:calf ratios, moose calf survival in the wolf removal block exceeded the one in the control area in 2 years out of 4, but the difference was statistically significant in only 1 case. Calf survival was significantly higher in the bear removal area than in the control block in 2 winters out of 3. It was impossible to detect a clear response to the treatment for moose density. The inconclusive results can be explained by too weak a treatment, annual and regional variations, sampling errors, limited sample sizes, small and close study areas.