PS 11-36 - Effects of anthropogenic mortality on wolves: Does demography matter?

Tuesday, August 9, 2016
ESA Exhibit Hall, Ft Lauderdale Convention Center
Heatherlee Leary, Natural Resources, University of Arizona, Tucson, AZ and David Christianson, School of Natural Resources and the Environment, University of Arizona, Tucson, AZ
Background/Question/Methods

Recent changes in hunting regulations of wolves have led to intense debate centered on the effects of anthropogenic mortality on large carnivores. Some questions being asked include (1) does anthropogenic mortality add to natural mortality, or is it compensated for by decreases in natural mortality; (2) how many individuals can we hunt; and (3) do demographics play a role in the effects of anthropogenic mortality? The purpose of this study is to answer these questions using data on Greater Yellowstone wolves taken from state and federal annual reports. The third question in particular is relatively understudied. This is important because characterizing demographics will help us gain insight into what drives differences among populations of social carnivores. In practice, we can use this information to better determine sustainable limits on hunting for individual populations.

Results/Conclusions

Results indicate anthropogenic mortality of Greater Yellowstone wolves is additive to natural mortality, and the sustainable limit of take is no more than 22% of the population. The demographic we focused on was pup-adult ratio and whether anthropogenic mortality of pups (younger than one year) has an effect on population growth. We found that pup recruitment decreases as anthropogenic mortality increases, and population growth decreases as pup recruitment decreases. Therefore, the effect of increased anthropogenic mortality on pup recruitment may influence negative population growth. This suggests anthropogenic mortality of pups does matter. This relationship is highly correlative, and there is still work to be done, however it is a first step to characterizing the role of demographics. Future directions include incorporating other demographics such as the proportion of pups to adults killed in hunts, social status of wolves killed, sex-ratio, and pack sizes. Overall, the final report will enhance science-based decision making for hunting regulations of large carnivores.