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DNR studies wolf behavior as hunting season approaches

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John Erb
DNR wolf research biologist John Erb inspects the frozen carcass of a wolf in a DNR laboratory in Grand Rapids. The wolf was killed by federal depredation trappers after complaints of livestock attacks. Erb uses the specimen to train DNR staff who will process wolf carcasses brought in by hunters during the upcoming season.
MPR Photo/Tom Robertson

At the edge of Itasca State Park, expert wolf trapper Barry Sampson is setting traps.

But Sampson, a wildlife biologist for the state Department of Natural Resources who has trapped wolves for 20 years, has no intention of harming the animals. He just wants to catch one.

Minnesota's first-ever managed wolf hunt gets underway in about two weeks, barring a successful legal challenge that could stop the hunt. In the meantime, state wildlife managers hope to gather information on Minnesota's wolf population. Since 1974, when federal officials put wolves on the endangered species list, their numbers in Minnesota have grown from a few hundred to about 3,000 five years ago, when researchers conducted the last wolf population study.

DNR officials say there are about 500 wolf packs roaming much of northern Minnesota.  Earlier this month, the opportunity to learn about wolves and their behavior brought Sampson to the edge of a quiet road outside the park.

"The odds are pretty good that in the next three days they're going to come trucking by here," he said. "It might not be the whole pack yet, but this trail gets a lot of traffic by wolves."

Over the summer and fall, Sampson captured 15 wolves from more than a dozen packs scattered across the state. Those wolves are now wearing collars equipped with GPS tracking devices.

Including some federal, tribal and private collaring programs, there are about 40 packs with collared wolves. The GPS devices will provide key data on territory size, and help the DNR do aerial wolf counts this winter, part of its five-year population survey. It became a requirement when wolves came off the endangered species list. 

Barry Sampson
DNR wildlife research biologist Barry Sampson uses his own bait mixture to lure wolves to the trap. It contains ground up bobcat -- taken from carcasses turned into the DNR by trappers -- along with beaver castor and a little bit of skunk.
MPR Photo/Tom Robertson

After Sampson buried and concealed the trap along the road, he used homemade bait to make it more attractive for the wolf.

"I mostly use bait that we mix up ourselves, and it's rotten bobcat," he said. "We cut it into chunks and grind it up, and then I add some beaver castor, a little bit of skunk. You can smell it."

It's a recipe only a wolf would love. The putrid scent lures them close to the trap. When the wolf steps on the pan of the trap, a steel jaw snaps shut onto the wolf's leg. The trap's teeth are made of rubber, so they don't break the wolf's skin.

Sampson said when he approaches captive wolves the breeding males will typically sit down and howl. But most wolves are quiet and submissive.

Wolf trap
Traps used by the DNR for catching wolves have jaws of steel, but the trap's teeth are made of rubber, so it doesn't break through the wolves skin.
MPR Photo/Tom Robertson

After carefully sedating the animals with a syringe attached to the end of a seven-foot pole, Sampson removes them from the trap.

"Once I get the collar on, then I put ear tags on and we take blood samples," he said. "Then I weigh him and we take a bunch of body measurements, and ... we may take an ear punch to collect a DNA sample."

In a basement laboratory freezer at the DNR's regional headquarters in Grand Rapids, wolf research biologist John Erb picks up the frozen carcasses of several dead wolves. One of them has bared teeth, as if frozen in mid-snarl.

"This animal here is a male, probably about two years old," Erb said. "We have a female here as well, I don't know the age ... and I believe there may be a young pup down there below."

Warning signs
DNR trappers put up signs warning pet owners that wolf traps are set in the area. The photo has been altered to redact the contact information.
MPR Photo/Tom Robertson

Erb said the frozen wolves were killed by federal trappers in response to complaints the wolves were killing livestock. He uses the specimens to train DNR workers who will process carcasses brought in by wolf hunters this fall.

Over the past few decades wolves have saturated their territorial range, Erb said, to the point that there are now about four wolves per 40 square-miles of territory.

"I believe that we have a higher density of wolves, at least in northern Minnesota where they are now, than we maybe ever had historically," Erb said. "And the reason is because of the higher abundance of deer, which wasn't here, or didn't exist 100 years ago. The forests were different. While there were moose and in some places caribou... the amount of meat per square mile was probably lower."

Biologists say the overall wolf population can vary greatly over the course of a year. After pups are born in the spring, the summer population in Minnesota can be as high as 5,000 wolves. But not all of those wolves will survive.

Wolf skull
A wolf skull sits in a basement laboratory at the DNR's regional headquarters in Grand Rapids. DNR biologists are hoping data collected from the upcoming wolf hunt, combined with a new population survey now underway, will offer new insight into the behavior and habitat of Minnesota's wolf population.
MPR Photo/Tom Robertson

Erb expects new count numbers compiled next spring, to again reflect a stable population.  He doesn't expect the upcoming hunt to dramatically affect overall wolf numbers, even if hunters and trappers take all 400 animals allowed by the DNR.

But data biologists collect from the hunt could shed new light on wolf behavior. While hunters and trappers can keep the pelt, the carcasses must be turned over to the DNR. Biologists will note the age and sex of the animal and where it was killed.

Erb says they'll also collect tissue samples that will help predict population trends in the future.

"On all of the females we will remove the uterus from them, and can do counts on that to determine what the litter size was," he said. "At each place an embryo pup was born, where the embryo detaches from the uterus, it leaves a scar. So basically what we count is these placental scars. So if there were seven scars that would be an indication that seven pups were born."

Data from hunters will show which age classes of wolves are most likely to be killed during the hunt. It may show how geography and habitat play a role in wolf vulnerability.

Erb said information from the GPS collars might show how wolf pack behavior is affected by hunters and trappers on the landscape.

Some environmental groups contend a wolf season in Minnesota is premature. Among them is the Center for Biological Diversity and Howling For Wolves, which appealed to the state Supreme Court to stop the hunt.

But Dan Stark, a wolf expert for the DNR, said allowing hunters and trappers to kill up to 400 wolves will still leave a population that's sustainable.

This year, application and license fees for the wolf hunt will raise about $300,000 in state revenue.

Stark said that money will pay for more wolf monitoring and research. The hunt also could help reduce the number of cases in which wolves attack livestock or pets, which have been on the rise the past few years, he said.

In fiscal year 2012, Minnesota paid out a record $154,136 to residents whose livestock or pets were killed by wolves. Last year, federal and state trappers killed 215 wolves in response to verified complaints. So far this year, those trappers have killed 237 wolves.

The main goal of the wolf plan is to ensure the long-term survival of the wolf in Minnesota and to address conflicts between wolves and humans.

The hunting season for wolves will run concurrently with the deer season that begins Nov. 3. A second rifle and trapping season is set for Nov. 24 through the end of January.