Wildlife Conservation Grants for Graduate Student Research
Tracking the Pack

Wolf pup

A wolf pup awakes after getting a radio transmitter in its ear.

For close to 30 years, timber wolves have been migrating into Wisconsin from Minnesota and multiplying. Wolves in Wisconsin now number 335-354, according to the Department of Natural Resources. Their numbers are high enough that the Wisconsin DNR held statewide hearings in November on a proposal to remove wolves from the state’s threatened-species list. Despite this increase in the overall number of wolves, individual wolf packs remain very small. Wildlife experts are not sure why.

After two years of tracking wolf packs, researcher Ellen Heilhecker has found some disturbing answers that may help to explain why the size of their groups isn’t growing. Her research could affect how the DNR manages wolves.

Heilhecker is a graduate student in natural resources at the University of Wisconsin – Stevens Point who has loved wolves ever since seeing her first pictures of them as a girl. Two years ago she decided as her master’s thesis to track what happens to wolf pups (under a year old). She located several wolf packs near Black River Falls and the Necedah National Wildlife Refuge as well as on privately owned cranberry bogs in Jackson and Wood Counties.

The Zoological Society gave Heilhecker $4,000 in research grants, enabling her to place transmitters in the ears of the pups she trapped. “I had no way to follow the pups until the grants,” she says. Now, with an antenna mounted on her truck, she follows as the pups move. She works cooperatively with DNR wildlife experts who use airplanes to track wolves they’ve equipped with radio-transmitter collars.

Wolf pup

A 4-month-old wolf pup at the Zoo in 1999.

Heilhecker’s research focused initially on following 10 pups from just three packs. By her second year, she was building upon that research by tracking six pups in five packs. Some pups came from the packs she had observed earlier. Sadly, she found that four of the first pups she’d tracked already had died, though she found only one of them in time to analyze what caused its death. The pup had contracted mange, a tiny mite that burrows beneath the skin, causing such intense itching that the pup had scratched off much of its fur and was 50% bald. It’s hard to know if the mange lowered the pup’s immune system, making it more prone to a fatal case of distemper, or if the animal was too weak from mange to find enough protein to overcome the disease.

What surprised her was the speed with which mange was spreading. The mite can survive for weeks; so a pup can catch it simply by lying down where an infected animal has been. “We saw wolves that were 50% to 85% bald. And if the wolf doesn’t grow its hair back in time, it will freeze to death in the winter.”

Another pup Heilhecker was tracking was killed after being hit by a car. A mother and her pups had gotten into the habit
of playing in the middle of the highway.

A major surprise cause of death came when a farmer found one of the pups dead in his field. She had been shot. He saw her tag and reported it. The surprise? The farmer was in Indiana. This was the first Wisconsin wolf known to have migrated south of Wisconsin. If one went south, others could, too – heading into population centers.

The federal protection status of timber wolves has been downgraded from endangered to threatened, but public hunting of wolves still is not allowed even though some farmers who have lost cattle to wolves are pushing for the right to kill the predators. Federal agents will kill problem wolves, and agents killed 17 wolves between April and November last year in Wisconsin. Wisconsin DNR officials, however, would like more flexibility in dealing with problems.

“Results of my study will give the DNR new information to better predict the state’s wolf population growth and aid in wolf management,” says Heilhecker.

By Fran Bauer