In the span of a human lifetime, gray wolves have re-established their presence in Montana’s mountains and forests.

Human settlers had driven most of the predators out by the early 1930s. But beginning in the 1970s, Endangered Species Act protections and re-introductions fostered a recovery. Montana’s wolf population has grown from about 50 confirmed animals in the 1990s to nearly 500 today.

The recovery is often hailed as a success story for wildlife management. But now, the wolf population’s growth is making management tougher.

Wildlife planners need a sense of how many wolves they need to protect. In past years, the U.S. Fish and Wildlife Service and Montana Fish, Wildlife and Parks have gotten that information using a minimum count — a physical survey of animals, one that assumed some would be missed.

“Minimum counts worked really well back in the day when there was a lot of money available for monitoring from the federal government, and when the wolf population was small enough that you could go out, and track, and count wet noses,” explained Mike Mitchell, unit leader of the University of Montana’s Cooperative Wildlife Research Unit.

“But the wolf population is too big for that now, and there’s not as much money to monitor them,” as the federal government hands management off to the state.

Mitchell is one of the scientists developing a newer method to track animal populations — not by counting, but by estimating.

Called patch occupancy modeling (POM), it’s been tested for a decade by Montana Fish, Wildlife and Parks. In October, the agency received a $50,000 grant from the Rocky Mountain Elk Foundation to hone it further. Questions linger about its suitability, but POM is now poised to replace minimum counts as Montana’s preferred wolf tracking method.

Mitchell explained how the method works. First, researchers establish a wolf pack’s average territory size using data collected by radio collars.

Then, “you break up Montana into this grid, [and] each of the grid cells is equal to the average size of a wolf pack’s territory.”

“And then we use hunter surveys to evaluate whether each of those cells are occupied by a wolf pack” Nearly 60,000 responded in 2014, according to last year’s annual wolf report.

Hunters’ not seeing the animals doesn’t necessarily mean they’re not there. If a cell yields no reported sightings, the question becomes, “How well can we estimate whether a cell where wolves weren’t seen was actually occupied?”

“If you take the environmental conditions that can affect whether wolves are really there or not, or affect how likely hunters are to see them, then you can estimate the probability that wolves were there but just weren’t observed.”

“Once we have these estimates of occupancy across all of these cells, that tells us how much area that is occupied by wolf packs.”

Multiplying the estimated number of occupied cells by a wolf pack’s average size gives a total wolf population.

The results, recorded in Montana’s Gray Wolf Conservation & Management 2016 Annual Report, follow the same general trends as minimum counts, but tend to range higher.

“The estimated number of wolves ranged from 24 pecent larger than the minimum verified number of wolves in Montana packs in 2008 to 61 percent larger in 2014,” the authors observed.

Mitchell, other scientists and state officials maintain that the state is due for a change in wolf monitoring practices. From 2011 to 2016, the Fish and Wildlife Service gradually turned management of wolves over to the state. That hand-off has meant fewer dollars for the man-hours, long drives and flights that minimum counts require.

Patch occupancy modeling recently emerged as a low-cost alternative. Over the past two decades, the method has been applied to species ranging from tigers in India to owls in the Pacific Northwest. Explaining the Rocky Mountain Elk Foundation’s recent decision to support the state’s use of this program, the group’s communications director, Mark Holyoak, said that it “allows researchers and wildlife managers to get a grasp, get a handle on how many animals really are out there and where they are.”

“From our standpoint that’s really important to know when it comes to applying wolf management and looking at the overall wildlife management picture, so that’s why we’re involved.”

Half of the foundation’s grant will fund radio collaring and management of “problem wolves.” The other half will support a joint FWP-University of Montana effort to develop the method further. Holyoak said that it’s “really up to them, just to apply the funding in the best manner that they can.”

One of the researchers who developed the method, retired U.S. Geological Survey scientist Jim Nichols, said the method used by these researchers “is viable and [the] UM and Parks folks are knowledgeable.”

But he added that Montana is finding a new use for patch occupancy modeling.

“This is one of the first situations I know of where it would have to do with a hunted species.”

The wolf report predicts that modeling “will provide utility for directly informing decisions about public harvest of wolves.”

Some in the environmental community support the shift.

“I see no reason for concern,” Tim O’Brien, senior scientist at the Wildlife Conservation Society told the Daily Inter Lake.

“The method has potential for improving the monitoring of wolves in a cost-effective manner.”

But other conservationists have doubts.

“We’re very skeptical that anything that the Rocky Mountain Elk Foundation puts money behind with regards to carnivores...is going to be beneficial” for those animals, said Marc Cooke, president of Wolves of the Rockies.

“We believe the way they gather intel, through the hunting community, is a biased source,” one with an incentive to over-report wolves to ensure higher hunting quotas. “The information that they’re gathering is garbage.”

Intentional or not, the problem of “false positives” ­— erroneous wolf sightings — has “been a source of concern for us all along,” Mitchell said.

He and Nichols explained that checking the false-positive rate for wolves that had been radio-collared enables researchers to predict what it would be on the state level, and revise the estimate accordingly.

Kevin Podruzny, a statistician at Montana Fish, Wildlife, and Parks, said University of Montana researchers are currently working to determine how much of an effort is needed to provide that data.

Meanwhile, Montana must maintain at least 100 wolves to avoid triggering a U.S. Fish and Wildlife Service review of their status. Minimum counts are already dropping, and Cooke suspects the state “just wants to keep [the number of] confirmed wolves above the federal minimum.”

With these concernes growing, the shift to patch occupancy modeling may spur more debate about how closely Montana should watch its wolves.

However that debate turns out, “I don’t foresee a time when we’re not going to be monitoring at all,” Podruzny said.

Reporter Patrick Reilly can be reached at preilly@dailyinterlake.com, or at 758-4407.