Badgers are important predators, especially in sandy soils, savannas and grasslands.
Digging up dirt about badgers
Genetics research will shine light on Wisconsin's mysterious animal.
Kathryn A. Kahler
Perhaps the popular UW fight song would be more accurate if the words read, "If you want to see a badger, just come along with me by the bright shining light of the moon." That's when you're more likely to catch a glimpse of one and why they're such elusive creatures.
Two research studies – one underway and the other planned to take up where the first leaves off – are designed to tell us more about these solitary, nocturnal animals for which our state and UW mascot are known.
"There are a number of good reasons to study badgers, but if for no other reason, why not because we're the Badger State?" asks Dave Sample, grassland community ecologist with DNR's Bureau of Science Services.
"Other than a few studies mostly from western states and Canada, we don't know much about badgers – how many are out there, where they live, how they use Wisconsin habitats and what they eat. They've been protected from harvest in Wisconsin since 1955 but we would like to know if a decline in observations over the last decade means we should do more. We would like to determine if there's good reason to upgrade them to a Species of Greatest Conservation Need. Right now badgers are identified in the Wisconsin Wildlife Action Plan as a species for which more information is needed."
Sample has been a "badger fan" since the mid-1980s when his research of grassland birds took him to Conservation Reserve Program (CRP) lands across the state. When the federal program – designed to convert marginal cropland back to more natural grassland – was first instituted in the mid-1980s, he saw very little sign of badgers in the new CRP fields. Twelve years later, he was surprised by the number of burrows evident on the increasing number of acres that had been converted from corn and soybeans to grasses.
"Badgers play an important role as predators in the grassland system in Wisconsin," says Sample. "Predation is the largest cause of nest failure for declining populations of grassland birds and one of the major predators of those birds is the 13-lined ground squirrel. And it just so happens that one of the badger's favorite foods is the 13-lined ground squirrel."
Badgers are also amazing diggers, capable of displacing five bushels of soil at a single site while searching for prey. "It almost looks like they sink into the ground as they disappear after their prey," says Sample.
Badgers spend most of their lives on the same home range – up to a square mile for females and two square miles for males, according to an Idaho study. In Wisconsin, a study led by LeRoy Peterson in 1975 concluded that badgers are more commonly found on light, sandy soils in agricultural areas covered with grassy vegetation, and where there is an abundance of 13-lined ground squirrels. Peterson and his team surveyed trappers, Conservation Congress delegates, field biologists and wardens, and appealed for public reports of badger sightings. The study found badgers in all but a few counties in the northeastern forests where the heavier, wetter soil is not favorable to their digging. They were more commonly reported in the central and west central parts of the state. Their population was roughly estimated at 8,000 to 10,000 animals.
Two decades later, DNR summarized the "Status of Badgers in Wisconsin 1987-1998" by compiling badger observations from field personnel who regularly report sightings of mammals like American marten, black bears, bobcats, coyotes, fishers, foxes, wolves, jack rabbits and otters. The 12-year analysis showed badgers were present in every county except Milwaukee, with highest observation rates in northern and central Wisconsin where sandy soils and jack pine savannas are prevalent, especially Douglas, Burnett, Bayfield, Langlade and Dunn counties. The report concluded that this broad statewide distribution suggested the badger population was relatively healthy.
In the decade since, annual mammal surveys show a slight decline in the long-term average of badger sightings. That's one of the reasons that Sample and other DNR researchers have been partnering with the University of Wisconsin-Milwaukee since spring 2009 on the Wisconsin Badger Genetics Project. The study hopes to answer such questions as where badgers live, how many badgers there are in Wisconsin and how badgers move across the landscape.
The study employs an up-and-coming method called genetic sampling that is increasingly used to study challenging species. A report from British Columbia explains why it's such a challenge to census badger populations.
Emily Latch, the UW-Milwaukee professor heading up the project, is confident that genetic sampling will help bridge the information gaps.
Her team's study relies on reported sightings of badgers, their burrows and road-killed carcasses. Road kills are sampled by clipping a small triangular piece from the animal's ear. When a burrow is reported, Latch or her assistant travel to the site and install a hair snare that snags tufts of hair as the animal leaves or enters a den. Back in the lab, DNA extracted from these sources is used to generate a unique genetic profile for each individual animal and allows subsequent identification if the animal is encountered again or can establish if a live animal was related to one of the road killed specimens. Coupled with spatial information for each sample (like GPS coordinates, or other mapping information) researchers will be able to get a better handle on distribution, the kinds of habitat badgers occupy across the state and perhaps identify features of the landscape that may prohibit or facilitate gene flow among Wisconsin's badgers.
"Genetic information is useful for wildlife conservation in a general sense," says Latch, "because it provides a detailed picture of animal behavior, natural history and movement patterns that can't always be recognized through observation. Genetic information is particularly useful for elusive species such as the badger where it is difficult or impossible to observe the animal for extended periods."
Latch and her graduate student assistant, Liz Kierepka, built on work started by Brian Sloss of UW-Stevens Point. They currently have collected about 110 samples. "The response from citizens has been wonderful," Latch reports. "Since we first asked last March for people to report sightings, we've gotten 150 to 200 phone calls, e-mails and photos. It seems everyone is really excited about badger research in Wisconsin."
When a report is received and a badger is positively identified, Kierepka follows up with an on-site investigation.
"The best identifications come from trail cameras," says Kierepka. "In those cases, I pretty much drop everything and drive to the site. Early on, most burrow sightings came from Dane, Iowa and Marquette counties, and mostly from prairie habitats. But we found as the seasons changed and more people were out enjoying nature, the reporting areas expanded. There were more reports from northern counties like Ashland and Douglas from people vacationing in places like the Chequamegon and Nicolet National Forests."
Once on-site, Kierepka checks out the area, trying to be as loud as possible to announce her presence. Badgers are well known for their ferocious disposition. If cornered they will fiercely defend themselves and their young, but if they're given room, they will retreat to their burrows.
"A badger burrow is pretty conspicuous and almost always found on a hillside," Kierepka explains. "If I can pull hair or feces out of a burrow, that's the easiest way to get a sample. But nine times out of 10, that doesn't happen so I set up a hair snare. I try to set up snares on multiple entrances, but especially the main entrance, which tends to be dug out better, has more dirt piled up and stinks. The snare is made of metal fitted with a strip of carpet gripper and two large spikes, which are shoved into the ground over the hole."
Kierepka returns the next morning to check for hair, marks the sample and takes it back to the lab for analysis.
Kierepka remembers the first badger she saw in Marquette County.
"She was an itty, bitty pregnant female. In the photo that was sent, she looked like a beach ball. The landowner said, 'We've got a hole in our yard, can you come catch it?'
"I had heard stories of them growling and when I got there it was early in the morning and had just rained. I found the badger redigging her hole. When she saw me, she backed into her hole and started growling. The best description I can come up with is that she sounded like an old man snoring."
The study is still in its infancy, but preliminary findings suggest that badgers may be less specialized than originally thought.
"Prevailing thought out west is that they're a grassland animal," said Kierepka. "In Wisconsin we're finding they will use other kinds of habitat like forest edges – like those in the Nicolet and Chequamegon National Forests – as well as dirt roads or driveways. There's an extensive burrow complex just off I-94 at a busy interchange in Dane County. And of course there was the now famous badger photographed and videotaped on YouTube who wandered into the post office in Milwaukee. With that confirmed sighting, we can now say badgers are present in every county in the state."
Building on the four-year UW-M genetics project, Dave Sample and other DNR and UW researchers plan to continue the genetics study statewide. In addition, they will set up an intensive ecological study of badgers in an area of southwest Wisconsin and perhaps another region where traditional methods of capture, following marked animals and observation will paint a better picture of how badgers live, their age structure and reproductive output, what they eat and how they interact with plants and other animals within their habitat.
Latch says the badger genetic database will be combined with GPS locations for all samples and overlaid onto ArcGIS maps to create a complete picture of the distribution and relative abundance of badgers throughout Wisconsin.
"Also, the genetic data will tell us whether or not badgers exist in Wisconsin as one large connected population, or a number of smaller, isolated and genetically distinct populations," she concluded. "In the end, we'll have a better handle on this amazing mammal for which our state is named."
Kathryn A. Kahler writes for Wisconsin Natural Resources magazine in Madison.