Deer, wolf and hunting: Professor shines spotlight of data on a durable debate
November 15, 2012
When the Wisconsin gun deer season starts Saturday, Nov. 17, some hunters will be wondering about the impacts of the growing wolf population, and the first wolf hunting season in more than 60 years.
A primary justification for the season, which began Oct. 15, was to reduce wolf depredation on state's herd of white-tail deer.
Although wolves certainly prey on deer, Timothy Van Deelen, an associate professor of wildlife management at the University of Wisconsin-Madison, says that does not automatically mean that hunting more wolves will bring more deer.
The situation is just too complicated for that. Numbers are hard — and expensive — to come by, and raising the already high deer population may not be a good thing.
Looking at the available data, Van Deelen says the Wisconsin deer population is doing quite nicely, even as wolf numbers have grown. The impact of 900 wolves in a state with 30,000 square miles of wolf range and several hundred thousand deer is likely to be minimal.
"I'm a population ecologist, and it's a difficult question whether wolves are real competition for hunters," says Van Deelen. "There is the potential for competition, but everything about the evolution and life history of the white tail deer is designed to offset losses to predation."
Wolves hunt by chasing instead of ambush and may train deer to become much more wary, Van Deelen says, "so they may be much less visible to a hunter who is out for a week or so."
Van Deelen, who grew up hunting in the Lower Peninsula of Michigan, and continues to hunt deer, notes that wolves also kill coyotes, another deer predator, thereby reducing coyote impacts on deer.
In general, he says, scientists estimate that the average wolf kills 17 to 20 deer per year, which comes to about 20,000 kills in the northern two-thirds of Wisconsin.
"We don't know how many of them would have died from something else," he says. "Wolf predation on coyote is part of a compensatory mechanism that we don't fully understand."
To get reliable numbers on changes in the deer population and predation by wolves and others, Van Deelen is supervising two intensive, radio-collaring projects in collaboration with the Wisconsin Department of Natural Resources. Now in their third year, these projects are located near Winter in the Northwest forest, and Shawano, in the eastern farmland.
"As near as I can tell from DNR harvest and monitoring data, wolves are not causing a dramatic decrease in the growth rate of the deer population, and whatever level of competition is occurring must be trivial," says Van Deelen. "There are hunters who are unlucky to have a bad experience at the local level, but at the statewide level, I am not seeing significant wolf impacts."
Dense deer populations cause thousands of auto collisions, and damage tree plantings and native vegetation.
"Ecologically, the impact is across the board," Van Deelen says. "If you are a commercial forester, you worry about regeneration of trees with commercial value. If you are concerned about the biodiversity of forest floor plants, deer impact that. [UW-Madison botany professor] Don Waller has done lots of really rigorous research demonstrating that we are losing plant diversity at the same time that the deer population is increasing."
The problem, Van Deelen says, likely lies in expectations.
"In Wisconsin, we have a generation of hunters who grew up in 1980s, when the deer population was at a historic high level. Even though the deer population is only down a bit, they begin complaining that it's not as high as they think it should be, but their frame of reference may be unrealistic or incompatible with the conservation of other resources," he says.
"Numbers from outside sources are clear," Van Deelen adds. "Per square mile, in antlered deer, antlerless deer and trophy bucks, Wisconsin is at the top, compared to Michigan, Pennsylvania, Minnesota, Illinois and Iowa.
The Quality Deer Management Association, which is independent of the DNR, puts us third in the nation in terms of harvested bucks per square mile, and fourth in the nation in terms of antlered bucks in 2010. The Boone and Crockett club suggests that Wisconsin hunters have reported three times as many trophy class bucks per 1,000 square miles as hunters in Michigan and Minnesota."
"Taken together these statistics suggest that Wisconsin is a good place to be a deer hunter, whether your interest is in the opportunity to harvest any deer or the opportunity to harvest a trophy buck," says Van Deelen.
Controversy is stock-in-trade for wildlife managers, adds Van Deelen, who was critical of the preliminary report on deer management ordered by Gov. Scott Walker, but gave better grades to the final report, issued in June.
"It's always the same arguments," Van Deelen says. "People argue that there are not as many deer as there should be, or as many as the DNR says, yet since Aldo Leopold's time, the deer population has increased."