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Fri April 27, 2012
Scientists Dig into How Wisconsin Wolf Hunt Might Impact Population Stability
Wisconsin leaders recently passed a controversial bill allowing people to hunt wolves starting this fall.
The move came shortly after the federal government removed the animal from the endangered species list.
Friday, researchers from UW-Madison share what they’ve learned about the impact wolf harvesting could have on the stability of its population.
The team will present its findings in Duluth, where a range of interested people – from scientists to livestock producers, are gathering for an annual conference on wolves in the Great Lakes region.
WUWM Environmental Reporter Susan Bence met the Madison researchers before they departed.
We sit in a conference room, dominated by a larger than life portrait of Aldo Leopold.
Over three-quarters of a century ago, he lead UW-Madison’s game management program. It was the first in the nation.
Today, Wildlife Biologist Tim Van Deelen says he’s following in Leopold’s footsteps.
“We look at research that really is intended to inform the management of white-tailed deer, black bear, gray wolf,” Van Deelen says.
Van Deelen says scientifically-informed management is crucial to making sure wildlife populations strike the right balance in nature.
Van Deelen’s “toolbox” is far more sophisticated than Leopold’s , but comes with age-old tensions. In the case of the gray wolf........
“Much of the antipathy towards wolves has to do with their perceived or expected impacts on the deer population,” Van Deelen syas.
Three years ago, Van Deelen launched a wolf study in Wisconsin.
“At the time, there was already discussion about delisting wolves and so management authority would then return to the state and I said that we really need to understand the population dynamic of wolves in order to be able to craft a responsible management program,” Van Deelen says.
Scientists had already observed that during the first 20 years of the wolf’s return to Wisconsin, its population barely grew.
“Growth was sometimes positive, sometimes negative,” Van Deelen says.
Van Deelen says the slow growth could be attributed to the fact that, with so FEW wolves around, it was difficult to find a mate.
Alpha pairs breed and raise their young.
Then, if one of the Alphas dies....
“Gets hit on the road, gets poached, it may be a year or two before a new Alpha pair in that wolf pack territory breeds and a pack forms and they give birth. And having even a one year lag, can really depress the population growth rate,” Van Deelen says.
Van Dellen says scientists have also begun to document the cooperative nature of wolf packs. In addition to the “parents and their pups” – other adult wolves join packs and serve as “helpers”, such as when the Alpha heads out to hunt for food.
“A helper will stay behind and act as sort of a defender. There’s research that suggests that having those helpers in the pack facilitates the pups’ survival, “ Van Deelen says.
Van Deelen says in recent times, DNR wildlife biologists radio-collared wolves to collect data from the field.
“Wisconsin made the very fortunate decision when wolves began re-colonizing that they would monitor that. And there’s an unbroken radio telemetry record that spans the entire period of wolf recovery, which is just remarkable,” Van Deelen says.
It fell to PhD student Jennifer Stenglein to put the pieces together. She created a computer model reflecting what scientists have learned about wolf behavior in Wisconsin.
Her model features tiny wolf figures dotting northern and central Wisconsin – with each dot representing a wolf pack.
“And it’s shaded from dark to light as a probability of mortality; so higher mortality are lighter colors, and lower mortality are darker,” Stenglein says.
Stenglein says the “danger” zones are areas where uninterrupted forest gives way to agricultural land and roads - places where wolves are more likely to get into trouble.
She has put her model through the paces by introducing different hunting scenarios and running each hundreds of times to test its predictability.
For instance, what happens if hunters harvest wolves only in the “danger” zones or during wolf mating season. “ It becomes a pretty big deal, because of that pack structure being broken up,” Stenglein says.
Just days before our meeting, Stenglein and Tim Van Deelen met with DNR administrators to demonstrate how they could use the model to design Wisconsin’s hunt.
The agency has not yet set rules.
“We showed it to DNR managers with the idea that if they chose to use it, this is something that would be reasonable, because at least for five years, Fish and Wildlife Services is kind of looking over their shoulder to make sure the wolf management still ensures the security of the wolf population in the Great Lakes,” Van Deelen says.
U.S. Fish and Wildlife will closely monitor Wisconsin's success at maintaining its wolf population.
If it dips to 250 or below, the federal agency would re-impose endangered species status.
No matter how Wisconsin’s first official wolf hunt is designed, PhD candidate Jennifer Stenglein will plug its parameters into her computer model.
If it churns out the same outcome as what happens in the field, she’ll know she has a reliable wolf management tool to share.