Cover Story
Bearing South
With a growing population and expanding range, Wisconsin black bears are on the move. CALS researchers are studying their path to figure out where they'll end up.
A thousand feet above Dunn County in West-Central Wisconsin, Karl Malcolm sits hunched in the cockpit of a Cessna Skymaster as it follows the curves of the Cedar River. Below, the landscape bursts with autumn color, but Malcolm isn’t paying attention. His head is down, and his eyes are shut. His hands press headphones tightly to his ears. Long minutes pass as Malcolm, a graduate student in forest and wildlife ecology, is lost in silent concentration.
Suddenly his head comes up, eyes open now, scanning the ground below. “I’ve got one. To the left,” he calls out. “Strong now. Right here.”
Immediately the horizon tips on end as pilot Paul Anderson throws the plane into a steep turn to point the left wing, bristling with antennae, straight down. The Cessna makes tight circles around a wooded hill, an island of trees among the cornfields. Somewhere in that woodlot, or the tall corn that surrounds it, a 20-month-old male black bear is finding its way through the most dangerous year of its life.
A male bear’s life starts out pretty easy, but by the second year, it’s anything but. His once-protective mother pushes him away, and if he stays in the vicinity of other bears, he’s vulnerable to attack by older, larger males. So he strikes out, looking for a piece of bear-free ground to call his own. The journey could take him hundreds of miles, during which he’s likely to encounter houses, highways, hunters and countless other dangers.
A quarter century ago, Wisconsin bears didn’t have to roam far to find their own turf. A report published in 1982 by the state’s Department of Natural Resources estimated that Wisconsin had fewer than 5,000 bears, and the authors expressed concern that numbers were declining. The state no longer had a resident bear population south of Highway 64, an east-west road that passes 20 miles north of Wausau, and many experts doubted it ever would.
Today, largely due to hunting restrictions enacted in 1986, Wisconsin has an estimated 12,500 to 14,000 bears. While most of them still reside in the upper third of the state, some 1,500 of them live south of Highway 64. Bears now thrive in Wisconsin’s central forest, an island of oak and pine covering several million acres of Clark, Dunn, Juneau and Jackson counties. And they continue to push southward. Bears have been spotted around Madison and other southern Wisconsin communities, and in 2005, a jogger ran across one in a park in Cedarburg, a 20-minute drive from downtown Milwaukee.
These aren’t just wandering males, either. Sows with cubs have been spotted in several southern counties, says Mike Foy BS’79, a DNR wildlife manager for Rock and Green Counties, which lie near the Illinois border. “We’ve had some of these animals over-winter now,” he says. “A female with cubs is an indication that we’re on the way to having a resident bear population.”
If you live around rural areas, the prospect of having bears in the neighborhood is more than just a curiosity. Some welcome the idea—real-estate ads for vacation properties often play up the chance to see bears. Others dislike the nuisance of sealing up garbage cans and taking bird feeders inside each night. But for farmers, bears can be a headache. A trampling, feeding bear can leave a cornfield looking like a crop circle. In 2006, Wisconsin farmers made claims of $121,708 for damage done by bears. That same year, 19 bears were trapped on a single farm in Sawyer County.
Bear attacks on humans are very rare—often coming years apart, which is remarkable considering the thousands of times that humans encounter bears each year. But when they happen, they can be serious. In two separate incidents in 2007, Wisconsin deer hunters went to the hospital after startling bears.
All of this weighs on the minds of DNR wildlife managers, who are enlisted to help humans coexist with the state’s wilder residents. To deal with those questions, the DNR is helping fund a research project led by Tim Van Deelen, a CALS assistant professor of forest and wildlife ecology who studies the population dynamics of large animals. Along with graduate students Karl Malcolm, Dave MacFarland and Lizzy Berkley, Van Deelen is out to understand not just where the wild things are in Wisconsin, but where they are going.
Keith Warnke BS’90, a DNR game specialist, ticks off questions he hopes the research will answer: “Are (bears) going to go specifically into the next available patch of habitat, or do they just take up stakes, start walking and keep on going until they get to something good? Is there any way to predict which direction is going to be most suitable for the next dispersal wave of black bears?
“This is all useful, helpful kinds of management stuff that will enable us to prepare to be more proactive with bear range expanding into southern Wisconsin,” he says.
Back in the Cessna, Karl Malcolm nods at the landscape below—a tapestry of broad fields, dotted with woodlots, rural homes and hamlets and carved up by a labyrinth of roads. To the north, Interstate 94 carries a solid stream of traffic toward Eau Claire. “That bear has crossed this kind of landscape, crossed that freeway a couple of times, crossed the Chippewa River,” he marvels. “It has covered some pretty nasty territory. There are a lot of scattered woodlots, but that bear had to go through a lot of (land) that’s not good bear habitat to reach them.
“I don’t know how he crossed it,” he adds, “but I will when I get his collar.”
The bear Malcolm is following wears a $2,500 collar, equipped with radio transmitters and a GPS recorder that logs the bear’s exact position at least once every six hours. Last winter, Malcolm put collars on three male and seven female bears. (Only the males get GPS, since they wander more.) About every two weeks, he goes up on a DNR plane to check in on them, using radio signals to locate them. Once they den for the winter, he will track them down and retrieve their collars, giving him a day-by-day, mile-by-mile account of how they navigated their surroundings.
Given Wisconsin’s growing human population and its increasingly carved-up rural landscape, you might think bears wouldn’t fare so well outside of the deep woods. But some changes in rural land use are making it easier for bears to expand their territory, Van Deelen explains. He says that a shifting of lands away from agricultural production has created habitat that’s inviting not just to bears, but also deer, coyotes and other large mammals.
“A lot of farms that were active dairy farms 20 years ago are now hunting properties, or hobby farms, or part-time farms,” he says. “So the fencerows get thicker, and the woodlots get bigger over time. The transition zone between what’s clearly northern forest and what’s clearly high-production agriculture is becoming more friendly from the bear’s point of view.”
In fact, a model developed by Dave MacFarland, another of Van Deelen’s graduate students, shows there’s plenty for bears to like about central and even southern Wisconsin. MacFarland spent the past two years creating a profile of bear-friendly habitat, based on the characteristics of lands where bears thrive now. His analysis shows that there are hundreds of square miles in Wisconsin that are currently bear-free, but may not be likely to stay that way (see map, above).
MacFarland’s strategy involved some 2,000 pounds of bacon and 90,000 doses of the antibiotic tetracycline. With these, he made antibiotic-laced baits, which volunteers from the Wisconsin Bear Hunters Association placed in every township in bear territory. During 2006, they monitored the baits, checking for claw marks on trees to confirm they had been taken by bears.
One goal of the project was to get a better handle on Wisconsin’s existing bear population. DNR assessments are based on previous estimates and can grow inaccurate over time. MacFarland’s study, the most comprehensive independent bear survey in the state, uses math to recalibrate the agency’s model.
Researchers analyzed rib tissue from bears killed during the past two hunting seasons for traces of tetracycline to calculate how many bears in the harvest ate baits. Figuring that the ratio of bait-eating bears in the hunt should be the same as bait-eating bears in the total population, MacFarland then applied that ratio to the total number of baits taken to estimate the state’s total population.
At the same time, MacFarland assembled information about the locations where baits were taken, including remote-sensing data on landscape features and census data on human habitation. He then developed a model to pinpoint similar landscapes in other areas of the state. Among the regions tabbed as potentially bear-friendly—but still relatively bear-free—are the hilly Driftless region of southwestern Wisconsin and the Baraboo Hills, both of which are well-traveled by humans.
MacFarland says the model can help identify trouble spots where bears might interfere with human activities. He plans to incorporate locations where bears have caused agricultural damage to help flag areas where such problems are likely to occur in the future.
“Twenty years ago there were no bears in the central forest. Now there’s a strong, healthy population in the central forest, and we’re getting bears moving to the west,” MacFarland says. “That’s what we want to focus on: When can we expect populations of bears in Iowa County? Or should we?”
Even as MacFarland tests his model, Wisconsin bears seem to be confirming its validity. “We have bears pushing into Vernon County and Richland County, (and) a bear reported denning in Iowa County,” he points out.
Ultimately, MacFarland’s maps and Malcolm’s collars will provide wildlife managers with information about how a population of occasionally pesky animals is making its way across Wisconsin and into places where interactions with humans are inevitable.
But how many bears end up living in those places will not be up to the bears, points out the DNR’s Keith Warnke.
“It’s going to be determined by people,” he says. “Bear are dispersing into unoccupied but very suitable range. That’s where we need to work. We need to proactively think about how many bears are going to be tolerated there and about educating people about what it means to be living with bears.”
To Mike Gappa BS’70, a retired DNR wildlife biologist who now works with the Wisconsin Bear Hunters Association, it sounds a lot like the way things were in central Wisconsin a couple of decades ago, when wildlife managers felt sure no bears would take up residence south of Highway 64.
“The feeling back then was the animal will not exist in the central forest because people won’t tolerate the animal,” he recalls. “I always felt that the animal could exist here, and it pretty much depended on people’s attitudes. Bears are telling us by their presence that they can live with us. The question is, can we live with them?”
Forest Forensics
Lizzy Berkley goes biochemical to track what wild wolves are eating.
Watch out, Canis lupus, a.k.a., the wild grey wolf. Lizzy Berkley knows what you’re eating. Sure, you may have licked the blood of your last prey from your paws, but there’s a record of your deed that you can’t hide.
For Berkley, a graduate student in forest and wildlife ecology, the proof is in the fat.
Typically, researchers have a difficult time telling exactly what wild animals eat. They can make guesses by picking through scat for bits of bone and fur or examining the stomach contents of dead animals. But even these methods still reveal only what an animal ate last night. What about last week? Or last month?
Berkley and her advisor, forest and wildlife ecology assistant professor Tim Van Deelen, are experimenting with a new strategy, which traces telltale signs of an animal’s diet in its fat cells.
Every animal species has a unique mix of fatty acids. When one animal eats another, some fatty acids from the prey are deposited largely intact into the fat tissue of the predator, creating a signature that can be identified through lab analysis. Since fat accumulates over time, researchers can learn about what an animal has eaten for the past six months by studying a sample of its fat.
Guided by Van Deelen, Berkley is using the model to assess the diet of wild wolves in the upper Midwest. The goal is to determine how much wolf diets vary according to the prey available: Do they eat mostly what’s around and plentiful, or do they prefer a particular species if they can find it? Answers to these questions might help wildlife managers protect livestock or fragile populations of elk or moose.
Berkley’s model actually begins with dogs. To create a baseline for how prey species’ fatty acids show up in wolf tissue, she prepared hundreds of what she calls “fatsicles”—Dixie cups full of frozen moose, beaver, deer and cow fat—and fed them to a group of Inuit sled dogs, closely related to wolves. She then took tissue samples from the dogs and analyzed them using a gas chromatograph, an instrument that separates organic material into component compounds.
Next, she’ll compare those profiles to fat samples collected from wild wolves trapped throughout the Midwest. Since she knows what the dogs ate, she hopes that similar fat signatures will create a record of what the wolves have been feasting on, as well. It’s kind of like CSI: Up North, except smellier.