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Wolf population dynamics in the U.S. Northern Rocky Mountains are affected by recruitment and human-caused mortality

Authors

  • Justin A. Gude,

    Corresponding author
    1. Montana Fish, Wildlife and Parks, 1420 East 6th Avenue, Helena, MT 59620, USA
    • Montana Fish, Wildlife and Parks, 1420 East 6th Avenue, Helena, MT 59620, USA.
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  • Michael S. Mitchell,

    1. U.S. Geological Survey, Montana Cooperative Wildlife Research Unit, 205 Natural Sciences Building, University of Montana, Missoula, MT 59812, USA
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  • Robin E. Russell,

    1. U.S. Geological Survey, Northern Prairie Wildlife Research Center, 8711 37th Street, SE, Jamestown, ND 58401, USA
    Current affiliation:
    1. U.S. Geological Survey, National Wildlife Health Center, 6006 Schroeder Road, Madison, WI 53711, USA.
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  • Carolyn A. Sime,

    1. Montana Fish, Wildlife and Parks, 1420 East 6th Avenue, Helena, MT 59620, USA
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  • Edward E. Bangs,

    1. U.S. Fish and Wildlife Service, 585 Shepard Way, Helena, MT 59601, USA
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  • L. David Mech,

    1. U.S. Geological Survey, Northern Prairie Wildlife Research Center, The Raptor Center, 1920 Fitch Ave., University of Minnesota, St. Paul, MN 55108, USA
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  • Robert R. Ream

    1. Montana Fish, Wildlife and Parks Commission, 1420 East 6th Avenue, Helena, MT 59620, USA
    2. Wildlife Biology Program, University of Montana, College of Forestry and Conservation, Missoula, MT 59812, USA
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  • Associate Editor: Kevin McKelvey.

Abstract

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). We replicated their analyses considering only those years in which field monitoring was consistent, and we considered the effect of annual variation in recruitment on wolf population growth. Rather than assuming constant rates, we used model selection methods to evaluate and incorporate models of factors driving 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 document that recruitment rates have decreased over time, and we speculate that rates have decreased with increasing population sizes and/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. Estimates of positive wolf population growth in Montana from our top models are consistent with field observations and estimates previously made by MFWP for 2008–2010, whereas the predictions for declining wolf populations of Creel and Rotella (2010) are not. Familiarity with limitations of raw data, obtained first-hand or through consultation with scientists who collected the 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. © 2011 The Wildlife Society.

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