Spatial Search and Efficiency Rates as Components of Wolf Predation Risk

Scientific Disciplines
Biological Sciences - Terrestrial
Keywords
Biology
University of Montana
wolf
Canis lupus
gray wolf
wolves
College of Forestry and Conservation
predation
risk
Rangifer tarandus caribou
predation risk
search efficiency
anthropogenic linear
search efficiency rates
Rangifer tarandus
Authors
Years
Volumes
Volume 18, No. 1-4

Spatial search and efficiency rates as components 
Of wolf predation risk
Nicholas J. DeCesare* , Wildlife Biology Program, Department of Ecosystem and Conservation 
Sciences, College of Forestry and Conservation, University of Montana, Missoula, Montana 59812.
Mark Hebblewhite, Wildlife Biology Program, Department of Ecosystem and Conservation 
Sciences, College of Forestry and Conservation, University of Montana, Missoula, Montana 59812
Jesse Whittington, Parks Canada, Banff National Park, Box 900, Banff, Alberta, T1L 1K2 Canada
Lalenia Neufeld, Parks Canada, Jasper National Park, Box 10, Jasper, Alberta T0E 1E0 Canada
Mark Bradley, Parks Canada, Jasper National Park, Box 10, Jasper, Alberta T0E 1E0 Canada
Anthropogenic linear features are hypothesized to increase wolf (Canis lupus) predation 
risk for a threatened ungulate, woodland caribou (Rangifer tarandus caribou).  Previous 
research has shown that these features are selected by wolves while searching for prey, 
but their effect on the net efficiency of predation, measured in kills per day, has not been 
addressed.  We use resource selection and proportional hazards modeling to assess the 
spatial drivers of both search and efficiency rates of wolf predation in a multi-prey system.  
Topographic variation consistently affected wolf search rates and the predation efficiency 
of wolves while searching.  However, the effects of anthropogenic footprint upon the total 
predation risk imposed by wolves were mediated solely by changes to wolf search rate; wolf 
predation efficiency generally did not change with proximity to anthropogenic linear features 
as previously hypothesized.  Predicted models of the cumulative hazard encountered by 
wolves validated well with among-pack variation in kill rates, suggesting that spatial hazard 
models allow the scaling up of local heterogeneity to population-level dynamics.  Lastly, we 
estimated an integrated spatial model of relative predation risk as the product of both search 
and efficiency rates, which captured the distinct contributions of spatial heterogeneity to each 
component of risk.