Growl, you’re on canine camera

Researchers in Idaho are finding new ways to monitor wolves and moving largely away from expensive tracking collars that have been a cornerstone of wildlife biology for decades.

In their place, they are deploying hundreds of trail cameras across the state and tapping into the DNA of harvested wolves to unlock clues about their breeding success.

Earlier this year, the agency announced its latest estimated wolf population. At the end of 2019, the state had about 1,500 wolves. The estimate was the first to be built on statistical analysis from millions of photographs taken by an army of about 600 trail cameras.

The work is part of a three-year study said Katie Oelrich, large carnivore biologist for the Idaho Department of Fish and Game. By the time it wraps up, Oelrich said it may be possible to dramatically reduce the number of cameras in use.

The cameras are deployed in a vast grid made up of individual cells. Last spring and summer, the system captured more than 11 million images. Computer software was used to filter those photos down to about 1.5 million with something that could be a large animal in them. Fish and Game technicians and biologists then scrutinized those photos to see which ones had wolves.

Right now, some of the cameras are set up to detect which areas of the state are occupied by wolves, while others are deployed to determine abundance of wolves in particular areas.

“What we are trying to do is create a relationship between the occupancy model and the abundance estimate. So when occupancy is this, abundance is probably this. If occupancy is 50 percent in this cell, then wolf abundance is this,” Oelrich said. “Hopefully we won’t have to put out 600 abundance cameras in the state and only have to put out 200 occupancy cameras. But it takes a few years to build that relationship.”

It won’t be the only method used to monitor wolf numbers. Lisette Waits, a University of Idaho professor who runs the Laboratory for Ecological, Evolutionary and Conservation Genetics led a team that determined DNA extracted from harvested wolves can be used to estimate yearly wolf reproduction.

Waits’ lab has been doing genetic monitoring of Idaho’s wolf population since 2007.

When hunters and trappers in Idaho harvest a wolf, they are required to have the animal checked by a Fish and Game biologist or technician. During that check, a tooth is extracted from the animal.

Genetic samples from teeth determined to be from young-of-the-year wolves, are sent to Waits’ lab. She is able to analyze the DNA and determine the number of distinct sibling groups among all the different samples, usually about 100 in total.

Those sibling groups — young wolves coming from the same set of parents or young wolves that are not related to any others in the sampling group — represent different packs that successfully reproduced. It is similar to the breeding pair metric that was once closely watched.

“Going through all 100 of the samples and seeing which ones group as related and which ones have no relatives in the young-of-the-year data set, those are sibling groups,” Waits said. “So knowing the total number of sibling groups allows you to know the number of breeding pairs that produced all of the sibling groups.”

When Idaho was required to report its wolf numbers to the U.S. Fish and Wildlife Service, it had to tally breeding pairs, made up of two adult wolves that produced at least two pups that survived through Dec. 31. The metric was used to track reproduction.

The genetic analysis also tracks reproduction, although it can’t determine if a pack or breeding pair is intact at the end of the year.

“If we collect enough genetic data, we can get accurate estimates on the number of sibling groups, and our estimates from the genetic data alone were very similar to data Fish and Game was getting from actual observations,” Waits said.

For example, in 2014 Waits’ team estimated a minimum of 52 packs produced pups compared to an estimate of 55 made by the state agency. In 2015 Waits estimate was 62 compared to the state’s estimate of 69.

“So in 2015 both methods detected an increase in the number of breeding pairs across Idaho,” she said.

The work is unique, Waits said.

“It’s the first time anyone has tested this method or applied this approach for wolves or any other harvested terrestrial species.”

Oelrich said the method serves as a cross check to the other ways the agency is monitoring wolf numbers, a topic that is often controversial. She said she likes that it is closely related to the breeding pair measurement which was important in the process of removing wolves from Endangered Species Act protection and remains closely watched. The state is still required to keep a population of at least 150 wolves and 15 breeding pairs.

“It provides us an independent measure that relates to the old delisting criteria. It’s a fail-safe, “she said. “This is an independent measure that shows us how many reproductive packs we have.”

Barker may be contacted at ebarker@lmtribune.com or at (208) 848-2273. Follow him on Twitter @ezebarker.