Bear hibernation research could offer clues to aid human health
Northwoods Notebook
One Upper Peninsula predator conspicuously not out searching for food or a mate this time of year is the black bear.
Most people are well aware the bears still slumber in hibernation, tucked in a den or even just curled up in a hollow in the earth or base of a tree. By now, pregnant sows will have given birth, keeping the cubs warm, clean and fed even while maintaining its mostly torpid state.
Bears once were not classified as true hibernators because they didn’t show the extreme temperature drop of other hibernating species, such as chipmunks. But when other changes were taken into account, it fostered a new respect for what black bears manage to do while hibernating — or, more accurately, what they don’t do.
While chipmunks may be able to go into a seemingly deeper hibernation, lowering the body temperature to near-freezing, they must wake every few days to eat and eliminate body wastes. It’s why chipmunks spend the fall months building a stash of seeds and other food.
It also can leave these rodents vulnerable if a predator manages to reach them while locked in hibernation, as it can’t fire up the internal furnace fast enough to respond and escape.
Bears, in contrast, can go for months without needing to take anything in or pass anything out, said Cody Norton, large-carnivore specialist with the Michigan Department of Natural Resources’ bear and wolf program.
Yet a bear can rouse if threatened, Norton said. The sleeping bears researchers haul from winter dens to be collared for tracking aren’t still hibernating but have been tranquilized to be handled safely.
Now, black bears not only are viewed as true hibernators but efficient ones, able to conserve enough energy through the winter to survive on body fat yet remain aware enough react if needed.
That ability to go for months without the need to eat, drink, urinate and defecate has drawn interest from some unexpected areas of research.
Doctors are studying bear hibernation for clues that might hold hope for humans with kidney disease. Enduring such a long period without urinating, the bears that emerge in the spring have substantial kidney damage, Ron Korstanje, a researcher at the Jackson Laboratory in Bar Harbor, Maine, stated in a 2015 article on the lab’s website.
Yet the bears seem able to regenerate their kidneys back to full function, Korstanje stated in the article. “How does that happen?” Korstanje asked. “And if we figure that out, can we come up with treatments that can prevent or reverse kidney damage?”
He was working to do RNA gene sequencing of bear kidneys before and after hibernation to determine what changed, with the long-term goal of a possible treatment for humans.
Along with not needing to feed or eliminate waste, the bear’s ability to maintain muscle and bone mass during hibernation has scientists wondering if it might offer ways for astronauts to avoid the degenerative effects of long space flights, Norton said.
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The 23nd annual Great Backyard Bird Count started Friday and continues through Monday. The effort provides a snapshot census of sorts that can help researchers better gauge how bird species and populations are faring.
The global event asks that participants spend at least 15 minutes on one or more of those four days counting bird species and their numbers, at home or wherever they choose. That data then can be entered at gbbc.birdcount.org.
Again, this is a great and easy way to play “citizen scientist,” one that can include beginning bird watchers to experts.
The pickings might be a little slim in the region this year, as the number of winter species so far has been much reduced. “Chickadees, nuthatches, and goldfinches have been more spottily distributed, while northern finches like redpolls and grosbeaks remain absent,” Ryan Brady, Natural Heritage Conservation Program biologist with the Wisconsin DNR, noted in his weekly statewide birding report.
Yet it offers a good excuse to get outdoors or even just spend some quality time seeing what might appear at feeding stations at home. Last year, Bohemian waxwings — an infrequent winter visitor to the region — showed up at the right time at Six Mile Lake to be included in the count.
For more information, go to the National Audubon Society website at https://www.audubon.org/conservation/about-great-backyard-bird-count; or Cornell Lab of Ornithology website at http://gbbc.birdcount.org.
Betsy Bloom can be reached at 906-774-2772, ext. 240, or bbloom@ironmountaindailynews.com.