You are what you eat: Mapping gray wolf diet and parasites across three regions in Manitoba, Canada

Background/Question/Methods

Predators can significantly impact prey populations not only through direct predation, but also by acting as definitive hosts for their parasites and completing parasite life cycles. Gray wolf (Canis lupus) diet is generally composed of large ungulate species but also known to include various other species when main prey resources are limited. Prey communities can shift between regions, potentially altering parasite communities, their impact on populations and overall population dynamics. We investigated wolves and their prey species across Manitoba in regions of differing ungulate assemblages to determine the relationships between spatial location, diet, and parasite communities. We wanted to know if changes in prey availability were reflected in shifts in diet and parasite communities and the impact on trophic relationships of wolves and their prey. To examine these relationships we collected wolf carcasses from hunters, trappers, and road kill in winter 2011, 2012, and 2013 from northern, eastern, and western Manitoba. Each region is characterized by a different group of ungulates, with caribou in the north, elk and white-tailed deer in the west, caribou and white-tailed deer in the east, and moose in all locations. We reconstructed the diet of each wolf using stable isotope ratios of muscle samples from wolves and their prey in Bayesian stable isotope mixing models and compared diet estimates to parasite prevalence and abundance of each individual.

Results/Conclusions

Taeniidae cestodes, including Taenia hydatigena and Echinococcus granulosus, were present in most eastern wolves, reflecting a diet primarily comprised of ungulates, but nematodes were rare. White-tailed deer dominated the eastern wolf diet but caribou and moose still represented important prey in both years. Eastern wolves that ate more moose tended to have fewer cestodes, while more cestodes were found in wolves with a higher percentage of deer in their diet. Our results suggest that if white-tailed deer populations continue to increase, the prevalence and abundance of parasites in the wolf population could also continue to increase. Taenia multiceps has been documented in the northern region and may serve as an important parasite for northern wolves who consume mostly caribou, indicating a shift in parasite community due to changes in available prey. Shifts in parasite populations in the ecosystem, caused by changes to the environment, including logging, hunting, and climate change, that affect ungulate populations may lead to changes in parasite communities and impact population dynamics of their hosts.