Heavy rains and sodden fields in autumn often block Wisconsin farmers from harvesting cornfields before winter.
When that happens north of Highway 10, it’s no surprise weeks later when a combine cutting crops from the frozen fields kills or cripples denned-up black bears.
Contrary to assumption, not all bears burrow beneath stumps or underground to snore through winter. Bears can den in a culvert between crop-fields or beneath roads, or the thick upper branches of fallen trees. Still other bears curl into subtle nest-den depressions they scrape into the interior of standing cornfields, entrusting endless rows of cornstalks to block the wind and their thick pelt to absorb the sun’s warmth.
One might assume only male bears tolerate a nest-den’s austerity. But no, females with cubs also endure above-ground dens, turning their back into prevailing winds and letting snow drift tightly around them for added insulation.
A lone male bear cub is being treated by the Wild Instincts rehabilitation center near Rhinelander, where it was brought Jan. 3 after its den site in a northwestern Wisconsin cornfield was inadvertently destroyed when the crop was harvested a day earlier. Two female cubs from the den didn’t survive. — Wildlife Instincts photos
Nest-dens in cornfields work fine, of course, until an unsuspecting farmer returns with machinery and strips the protective cornrows, inadvertently evicting the slumbering bruin. Lone bears simply move into the next available den site. A sow with newborn cubs might try to move her brood to a new den if conditions allow. If that’s not possible, nature deems her life more valuable to the species.
The cubs’ survival odds, however, usually plummet when humans intervene, especially when cubs are days or weeks old. That situation played out in early January for a farmer combining a cornfield near the Dunn County and Barron County line. After seeing a black bear flee his combine Jan. 2, the farmer stopped and found three days-old cubs squirming where the sow once lay, their eyes not yet open.
The farmer contacted the Department of Natural Resources and the Wild Instincts rehabilitation center near Rhinelander the next morning, Jan. 3. A DNR conservation warden and wildlife technician drove to the farm, took the cubs, and drove them eastward to rendezvous with a Wild Instincts volunteer. The driver then took the cubs – two females and one male – and rushed them to the center for emergency care.
The bear cub drinks formula with high levels of fat and protein.
Mark Naniot, director of Wild Instincts, said the two female cubs had pneumonia, and all three arrived with diarrhea. The female cubs didn’t survive, but the male’s condition improved over the next week.
The farmer declined interview requests, so it's unclear how long the cubs were in his care, and how he fed and warmed them. Randy Johnson, the DNR’s large carnivore specialist, said the farmer told them he initially picked up the cubs but soon put them back in the nest-den. The man said the sow returned briefly and possibly moved her cubs a short distance, but then left. The farmer took the cubs home before nightfall because they appeared to be freezing.
Johnson was reluctant to second-guess the farmer, and doesn’t expect the DNR to issue any citations.
“From what we could gather, there was a lot of intervention before he contacted us the next day,” Johnson said. “Our preference would have been that he leave the cubs in the nest-den and disappear. If that had happened, the sow would have likely felt comfortable returning, and things probably would have been fine.”
Johnson said by the time the DNR was alerted the next morning, the best option was Wild Instincts, Wisconsin’s only rehabilitation facility able to treat bears. The facility has an intensive-care unit to provide the proper heat, oxygen and humidity for young wildlife. The center is also more rural than most wildlife-rehab sites, and includes a 40-by-115-foot enclosure with a pond and den area.
Only one of these three small bear cubs survived after being moved from a nest-den Jan. 2. Two died from aspiration pneumonia.
“Treating bear cubs is more a matter of desire to do it than being qualified to do it,” Naniot said. “Enclosures like ours can cost thousands to build, and the formula cubs require costs $600 to $700 per cub until they’re weaned. After that, they eat a lot of produce and other foods while growing. It costs upward of $5,000 to rehab them from early age until their release in fall when they start preparing to den. We handled 14 cubs in 2024, so do the math. It’s very expensive.”
Store-bought baby formula won’t sustain bear cubs. Naniot said baby formula contains about 26% fat and protein, while bear-cub formula is 30% protein and 50% fat. Further, most wildlife species are lactose-intolerant, so formulas for young wildlife have little lactose and use customized additives to meet each species’ needs.
Naniot said few people have the training, food or gear to nurse helpless wildlife, so it’s important to seek help immediately. Wild Instincts (https://wildinstinctsrehab.com) has a 24-7 hotline, (715) 362-9453, and volunteer drivers on call.
“People who find injured or helpless wildlife want to help and do the right thing, but it appears (the farmer) didn’t feed the cubs proper foods,” Naniot said. “All three had severe diarrhea, and he wasn’t able to warm them the way they needed. They might have been fed too soon while they were cold and inhaled some formula. The two females had aspiration pneumonia.”
“Our ultimate goal is to return the cub to the wild this fall,” Johnson said. “The Wild Instincts staff do a really good job. Most cubs that end up there do well. Cubs typically aren’t abandoned. Sometimes a den floods out in spring and the cubs get ‘rescued,’ but in some cases the mother is road-killed and the cubs are just sitting nearby, stuck.”
Naniot said Wild Instincts has been treating bears for 29 years and has only lost two cubs that arrived in satisfactory condition. In that instance, the center’s ICU malfunctioned.
Naniot stresses that most young wildlife people find aren’t “abandoned” or needing help. Their mother usually returns if humans leave and stay out of sight. When in doubt, Wild Instincts’ hotline operators are available to assess things. If intervention is needed, the facility contacts volunteer drivers to respond.
Wild Instinct drivers often average 20,000 miles annually, and bring wildlife to the Rhinelander facility from roughly 40 Wisconsin counties and, occasionally, neighboring states.