WOLF PREDATION ON MOOSE IN NORTH–CENTRAL BRITISH COLUMBIA

Abstract

Moose populations declined substantially following widespread salvage logging of mountain pine beetle affected forests in interior British Columbia (B.C.) in the 2000s. The impact of wolf predation on moose was not well-understood in the context of extensive landscape change. We monitored 33 wolves across 11 packs in 2 interior B.C. study areas: Prince George South (PGS), characterized by extensive salvage logging features, and John Prince Research Forest (JPRF), also affected by salvage logging but less intensively. Because predation risk is a function of wolf density, space use, and predation patterns, we required a better understanding of these factors to develop management recommendations that could minimize predation risk to moose. Based on mid-winter pack counts and home range size, wolf density was about 10 wolves/1,000 km² in PGS and 5 wolves/1,000 km² in JPRF. We identified 290 kills made by wolves, predominantly moose in PGS (87%) and JPRF (75%). Wolves in JPRF preyed on more elk and deer than did wolves in PGS, and at 10% of the kill sites we investigated in JPRF, wolves had killed black bears. We found moose calves at 27% of the moose kill sites, compared with mid-winter estimates of standing proportions of calves in the population of 13–20%. After accounting for probability of the collared wolf attending pack kills, we calculated that wolf packs in PGS killed a moose every 4-8 days in winter and every 8–11 days in summer. In JPRF, wolf packs killed a moose every 7–12 days in winter and every 19–26 days in summer. However, when we considered the number of wolves per pack in the 2 study areas, the kill rates per wolf were similar. Based on recent midwinter moose density estimates, these kill rates would equate to 7–20% of the moose population for PGS and 2–8% of the moose population for JPRF. These predation rates may not be indicative of predation rates during the moose decline in the 2000s, so it is important to consider the mechanisms that could contribute to changing kill rates, including differential use by wolves and moose of highly modified landscapes and landscapes exposed to recent change such as widespread logging or wildfire. Based on our 2 study areas, extensive salvage logging creates habitat features that may support higher wolf densities and larger pack sizes, particularly in landscapes where moose are the dominant ungulate species.