Monitoring White-tailed Deer in the Columbia Mountains
The vast majority of caribou herds in western Canada are declining. Intense human intervention has been successful in stabilizing three herds, yet only one has shown growth. Understanding and monitoring additional limiting factors that may be preventing population growth is critical for effective adaptive management and recovery. This project will evaluate factors influencing White-tailed Deer populations in the Columbia Mountains, to support management decisions in a high-stakes socio-economic landscape while simultaneously collecting baseline data in which to evaluate the efficacy of White-tailed Deer reductions, via increased hunter harvest.
Update: 11 deer collared in the North Columbia
In winter 2018-2019, deer were captured between Mica Dam and Revelstoke, in the Columbia North and Frisby-Boulder caribou ranges. Four White-tailed Deer does and three Mule Deer does were outfitted with GPS collars to monitor survival and cause-specific mortality. One White-tailed Deer fawn and three Mule Deer fawns were outfitted with VHF collars. One female White-tailed Deer mortality was investigated, with the cause of death determined as coyote predation. In future years, deer survival will be monitored and the sample size increased to 20-30 adult does. Cause-specific mortality and survival rates will be calculated, recruitment rates estimated and the doe:fawn ratio measured. The goal is to directly measure the survival and recruitment of White-tailed Deer populations, and incidentally Mule Deer populations, within the mountain caribou range. Additionally, this project will inform the missing knowledge of how White-tailed Deer populations contribute to increased abundance of wolves and cougars. Baseline data will be collected, in order to evaluate the efficacy of proposed White-tailed Deer reductions via increased hunter harvest.
Final report: executive summary
Southern Mountain Caribou (Rangifer tarandus) are provincially red-listed and federally threatened. Caribou declines are primarily linked to unsustainably high predation rates, largely due to high predator abundances supported by other ungulates such as moose (Alces alces) and deer (Odocoileus spp.). It is commonly reported that increased moose and deer abundance is directly caused by human disturbance to their habitat, largely in the form of forestry activities within old-growth forests that create an abundance of early-seral forage (Schwartz and Franzmann, 1991; Serrouya et al., 2011). However, whitetailed deer (Odocoileus virginianus) are also hypothesized to be expanding their range northward as winters become less severe (Dawe and Boutin, 2016; Latham et al., 2011). Deer have previously been found to be a significant food source for predators such as cougars (Puma concolor; Bird et al., 2010) and wolves (Canis lupus) in the Columbia Mountains. However, white-tailed deer population dynamics and the potential influence of deer on the wolf-cougar-caribou system have yet to be evaluated.
Diverse management actions are currently being undertaken to recover mountain caribou populations, including habitat protection, predator control, reduction of alternate prey, augmentation through translocations, maternity penning, and recreation management (Serrouya et al., 2019). As a result of these actions, the population within Columbia North has stabilized, but adjacent herds have continued to decline. Despite both white-tailed deer and moose being recognized as invading alternate prey driving the increase in predator abundance, only moose have been targets for alternate prey management thus far. Understanding white-tailed deer population dynamics will become important as additional caribou management strategies unfold, and as climates continue to favour the northward expansion of white-tailed deer.
Click the provincial database link below to read the full final report for this project.