Importance Of Recruitment To Accurately Predict The Impacts Of Human-Caused Mortality On Wolf Populations

Scientific Disciplines
Biological Sciences - Terrestrial
Montana Department of Fish, Wildlife and Parks
wolf population
human caused mortality rates
Volume 17, No. 1-4

Importance of recruitment to accurately predict the 
Impacts of human-caused mortality on wolf populations
Justin A. Gude,* Montana Department of Fish, Wildlife, and Parks, 1420 East 6th Avenue, Helena, 
Montana 59620,
Michael S. Mitchell, U. S. Geological Survey, Montana Cooperative Wildlife Research Unit, 205 
Natural Sciences Building, University of Montana, Missoula, Montana 59812, USA, Michael.
Robin E. Russell, U. S. Geological Survey, Northern Prairie Wildlife Research Center, 8711 37th 
Street, SE, Jamestown, ND  58401, USA, 
Carolyn A. Sime, Montana Department of Fish, Wildlife, and Parks, 1420 East 6th Avenue, Helena, 
Montana 59620,
Edward E. Bangs, USDI Fish and Wildlife Service, 585 Shepard Way, Helena, Montana 59601, 
L. David Mech, U. S. Geological Survey, Northern Prairie Wildlife Research Center, The Raptor 
Center, 1920 Fitch Ave., University of Minnesota, St. Paul, Minnesota  55108,
Robert R. Ream, Montana Department of Fish, Wildlife, and Parks Commission, 1420 East 6th 
Avenue, Helena, MT 59620, USA, and Wildlife Biology Program, University of Montana, College 
of Forestry and Conservation, Missoula, Montana 59812, 
Reliable analyses can help wildlife managers make good decisions, which are particularly 
critical for controversial decisions such as wolf (Canis lupus) harvest. Creel and Rotella 
(2010) recently predicted substantial population declines in Montana wolf populations due 
to harvest, in contrast to predictions made by Montana Fish, Wildlife and Parks (MFWP). 
Here we replicate their analyses considering only those years in which field monitoring was 
consistent, and we consider the effect of annual variation in recruitment on wolf population 
growth. We also use model selection to evaluate models of recruitment and human-caused 
mortality rates in wolf populations in the Northern Rocky Mountains. Using data from 27 
area-years of intensive wolf monitoring, we show that variation in both recruitment and 
human-caused mortality affect annual wolf population growth rates and that human-caused 
mortality rates have increased with the sizes of wolf populations. We also show that either 
recruitment rates have decreased with population sizes or that the ability of current field 
resources to document recruitment rates has recently become less successful as the number 
of wolves in the region has increased. Predictions of wolf population growth in Montana 
from our top models are consistent with field observations and estimates previously made by 
MFWP. Familiarity with limitations of raw data helps generate more reliable inferences and 
conclusions in analyses of publicly-available datasets. Additionally, development of efficient 
monitoring methods for wolves is a pressing need, so that analyses such as ours will be 
possible in future years when fewer resources will be available for monitoring.