MARQUETTE -- Tuesday's Facebook story of the day talks about animal hibernation. Our Facebook viewers wanted to know how are the recent mild temperatures affecting the sleep habits of hibernating wildlife?

Black bears in the wild spend every day stocking up for possibly their favorite time of the year: winter. And here in the U.P. every October, an estimated 12 to 15,000 of them curl up in dens, and they typically don't come out until Spring.

"It's critical, it's a survival tactic, so they are shutting themselves down in the U.P.," said wildlife biologist Brian Roell.

And they're not the only ones shutting down. Many types of fish, squirrels, raccoons and other rodents do the same. So why do some of our Facebook viewers say they've recently spotted the wildlife? Donna Lee Nelson-Hilborn wrote, "Our camp is toward Bruce Crossing, and we've seen bear tracks in the snow."

It's not a concern, experts said.

Recent temperatures have only peeked in the 40s. Black bears are not affected right now, but they might be if warm weather spans over a longer period of time.

"They start burning muscle and that can be pretty damaging, especially if there's not an active food source," Roell said.

But bears, like other species, never truly shut down. They're able to get up and move around which is probably why some of our Facebook viewers have seen squirrels this time of year. Wendy Anne Roth Cox wrote, "Sixteen fat squirrels digging up my block in Adrian every day."

Turns out a couple of warm days don't really affect the sleeping habits of animals that hibernate. In fact, some animals have even made a comeback due to the mild winters.

"Turkey vultures, Northern cardinals, Red-bellied woodpeckers, a lot of species that typically didn't winter here because it was too harsh are now able to survive," Roell added.