New study seeks cost-effective estimate of Montana wolves
April 28, 2014
Researchers from Montana Fish, Wildlife & Parks and the University of Montana released preliminary results today of a new technique for estimating wolf numbers in Montana.
The study was developed to produce a less expensive and more accurate population assessment that accounts for wolves not actually verified in the state's annual wolf count.
Statewide wolf population estimates were derived for the years 2007 through 2012 via a mix of rigorous statistical evaluations, wolf observations reported by recreational hunters during the annual hunter-harvest surveys, and Montana's annual wolf counts.
Results generally estimate a Montana wolf population 25-35 percent higher than the verified minimum counts submitted over the six-year period.
The study's results are contained in FWP's federally-required annual wolf report available online at fwp.mt.gov. That report shows Montana's 2013 minimum wolf count at 627, essentially the same as the past two years. The minimum wolf count is the number of wolves actually verified by FWP wolf specialists.
"The study's primary objective was to find a less expensive approach to wolf monitoring that would yield statistically reliable estimates of the number of wolves and packs in Montana," said Justin Gude, FWP's, chief of research for the wildlife division in Helena.
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The typical method used to document the state's wolf population focuses on ground and aerial track counts, visual observations, den and rendezvous confirmation and radio collaring to count individual wolves as required by the U.S. Fish & Wildlife Service. The verified count is used to fulfill Montana's obligation to submit an annual wolf population report to federal authorities to ensure wolves are being properly managed above standards that could trigger relisting as an endangered species. Those counts must continue through Dec. 31, 2016.
"This new approach is not only good science," Gude said, "it's a practical way for Montana to obtain a more accurate range of wolf numbers that likely inhabit the state."
From 2007 through 2012, FWP and UM's Cooperative Wildlife Research Unit directed a team of 11 researchers to determine the number of gray wolves in Montana by estimating the: (1) areas occupied by wolves in packs; (2) number of wolf packs by dividing the occupied area by average territory size; and (3) numbers of wolves by multiplying the number of estimated packs by average annual pack size.
For instance, population modeling for Montana's wolves in 2012—where actual counts verified a minimum of 625 wolves and 147 packs—predicted that 804 wolves and 165 packs inhabited the state. Similar estimates are not yet available for 2013.
Gude cautions, however, that future statistically accurate estimates will need to incorporate wolf harvest locations and how the harvest of wolves by hunters and trappers influences where wolves choose to live, their territories and pack sizes.
"Data on each of these aspects of wolf population size will give us a very solid assessment of the effects of harvest on wolf populations in Montana," Gude said.
By adding additional harvest information, Gude said specific predictions of the effects of different seasons or harvest quotas on wolf populations could provide information vital to establishing successful wolf hunting and trapping seasons in coming years.
"Perhaps the best future use of these statistical methods won't necessarily only be for monitoring and keeping tabs on wolf population numbers, but to better inform the complicated decisions that accompany the public harvest and management of wolves," Gude said.
–Montana Fish, Wildlife & Parks