Black bear wandering around Kincaid Park in the middle of winter? Here’s why.

A black bear was spotted last week in Anchorage’s Kincaid Park, the wooded and popular recreation area on the west side of town.

Some reported the bear eating grass or drinking water or just wandering around, according to the Alaska Department of Fish and Game. At least a few young skiers with the Nordic Skiing Association of Anchorage’s Junior Nordic League saw the bear off the snowmaking loop last Wednesday evening during a particularly busy evening at the park. They reported the sighting to their coach, Geoff Wright.

“I assumed they were looking at a moose or a large dog or a coyote, but probably not a bear,” Wright said. “It’s stories from 6- and 7-year-old kids and they say all sorts of funny things.”

Like many park users, Wright has spotted bears in Kincaid in the summer. But in his 20 or so years of skiing in the park, he said, he’d never seen a bear there in the middle of winter. Still, he told his group to turn around just in case. Later, another skier showed him a picture of the bear taken that evening. Bear sighting confirmed.

Fish and Game hasn’t gotten a report of the Kincaid bear since last Friday, so it has likely headed back to its den, said department spokesman Ken Marsh. The department is aware of bear dens in Kincaid.

“They usually don’t stay up long unless they have that consistent food source,” Marsh said.

But the midwinter bear spotting raises the questions: Why was the bear awake? Did it have to do with the warmer-than-usual temperatures last week? Do bears actually sleep all winter?

Sean Farley, a Fish and Game wildlife physiologist, didn’t see the Kincaid Park bear last week, but here’s what he said about why a bear might be wandering around Anchorage in January:

Weather plays a role in when bears head into their dens. In the Anchorage area, black and brown bears generally hibernate from late October or November to April or May, he said. Female bears that are pregnant typically go in earliest and come out the latest.

Farley described hibernation as a “spectrum of physiological adaptations” to conserve energy. Arctic ground squirrels, for instance, can drop their body temperatures to below freezing. Bears aren’t like that.

“They’re not out cold like ground squirrels, they’re more like a sleeping dog that can be roused pretty easily,” Farley said. “They’ll get up and move around and thrash around.”

For bears, hibernation means heading into dens and lowering their metabolic rate. Their body temperature lowers from roughly 101 degrees to about 90 or 91 degrees, Farley said. It’s a survival tactic to make it through the winter, when there’s little to no food available.

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During hibernation, bears usually don’t eat, drink, urinate or defecate. They’ll lose about 20 to 25 percent of their body weight. Mostly fat, Farley said.

Yes, they also sleep, but not the whole time.

Bears cycle through periods of deep sleep and periods of arousal. Their body temperature will increase a bit when they’re aroused. They might shift positions. They might poke their heads out of their den. They might even leave for a few hours and come back — that’s not common, but it’s not unheard of, Farley said.

“When we say ‘leave the den,’ they don’t usually go on big walks,” he said.

Pregnant bears will give birth just a couple of months into hibernation. They’ll nurse their cubs in their dens, despite not eating or drinking.

“They’ve got these newborn cubs that they’ve got to take care of. They can’t go to sleep and just be out of it,” Farley said. “The cubs can’t do anything. ... All they can do is eat and scream and that’s about it. She has to move them around and hold them close to her body so they can nurse. She has to clean them.”

It’s very unlikely that a female bear with cubs will leave its den in the winter, Farley said.

So, why might a bear head outside in January?

[Related: Six bears, one lawn: What’s going on in this Anchorage yard?]

A bear might get restless and want to stretch its legs, Farley said.

It’s also possible the bear went into a den too skinny. Its energy reserves might have gotten so low at some point that it prompted the bear to wake up and go look for food. It’s that or starve to death, Farley said.

Or, maybe a noise outside of the den stirred it when it wasn’t in a deep sleep. Farley noted, however, that he has photographs of snowmachine tracks that go over a den hole that’s covered in snow.

What about last week’s weather? Temperatures spiked to 44 degrees on Friday at the Ted Stevens Anchorage International Airport. Could that be why the black bear wasn’t in its den?

A goal of a bear den: To keep the cold out, Farley said. So mild fluctuations in outside temperature shouldn’t really impact bears in insulated dens.

“If they’re deep inside in some sort of den, maybe covered with snow, they’re insulated," he said. "So fluctuations in the ambient temperature outside the den don’t get reflected as strongly inside the den. Plus they’re in the den heating it themselves because they’re at least 90 degrees or so.”

[On a sunny June afternoon, a cinnamon-colored black bear sprinted through downtown Anchorage]

In the Anchorage area, black bears often den in trees. Both brown and black bears will also dig into hillsides and excavate a dirt den. Bears can den in many other places too, Farley said.

If high temperatures melt snow and that leads to a bear’s den getting flooded, that’s another reason the bear might head outside. It’ll likely try to find another den, Farley said.

If you see a bear in the middle of winter, give it space, just as you would in the summer, Marsh said.

“Maybe turn around, change your course, you don’t want to push it,” he said.

Really this time of year, Marsh said, it’s more likely you’ll come upon a cranky moose.

“It’s been a long winter and they’re starting to get a little nutritionally stressed,” Marsh said. “Be alert just like you would in the summertime and give wildlife their space.”