It’s bedtime for black bears

  • You can find signs of black bear on beech trees, which bears will climb for the tasty nuts. Here, you can see fresh claw marks (above) along with marks made in previous years (below). Courtesy of Eric Aldrich

For the Monadnock Ledger-Transcript
Tuesday, November 28, 2017 10:3AM

Imagine finishing a big, hearty meal on a raw, late-November night, going to bed, and waking up when winter is over.

You know you’ve thought about doing it.

That’s our black bears’ remarkable way of adapting to the challenges of cold winters, when food is buried under snow.

The process starts in fall, as bears start filling up on acorns, beechnuts and other fatty foods, also known as mast.

Pregnant females really gorge on those foods.

Andrew Timmins, bear project leader for the New Hampshire Fish and Game Department, shows the math: A 125-pound pregnant female can put on 60-plus pounds of body fat to sustain her cubs in utero and after they’re born, usually in January.

That wax-like fat is laid down between muscles in layers that can be a few inches thick.

The pregnant females are usually the first to hit the dens, often around mid-October. Females with cubs born the previous winter may go down in late-fall or early winter, often sharing a den to stay warm. Adult males will continue feeding as long as there’s a good mast crop, sometimes denning up as late as into January, according to Timmins. At some point, it’s not worth a bear’s energy to seek that food.

Hitting the Beech

On Nov. 12, as I was topping a hill in Hancock while deer-hunting, I encountered two yearling bears who were just as surprised to see me as I was to see them.

At 30 yards or so, they studied me for a moment, then turned and ran. One clambered up a nearby beech, while the other ran ahead, then stopped to look for what I presume was its sibling. The bear in the beech stayed for a few seconds, saw me taking in the spectacle, then bolted down the tree and scurried after its kin.

After their hasty departure, I could see that they had been spending days foraging in an extensive, mature beech stand on the steep east-facing slope. They had even been climbing beeches, pulling branches inward, trying to get every last nut.

While black bears are enjoying this year’s feast of acorns, they prefer beech nuts, Timmins said.

At some point in the coming days or weeks, they’ll stop eating. With their bellies full, a cold wind in the air and possibly some snow on the ground, the males will search for denning sites. They can be in the root space of a downed tree, under a brush pile, a dug-out space in the shelter of thick softwoods, or in the cavity of some rocky spot.

Perfectly comfortable den

While checking radio-
collared females a few years ago with Fish and Game biologists, we found a female denned up with three little cubs inside the root system of an upturned tree. After biologist Will Staats pulled out the tranquilized mother bear and her cubs, I crawled into the empty den. It was spacious and still warm, lined with some grass, perfectly comfortable.

When a bear is in the den, its body temperature drops by seven to eight degrees and its heart and breathing rate drops 50 to 60 percent. It may also awaken during warm days to forage a little before returning to the den. And some female bears will give birth to cubs in mid-winter while denning. So, it’s not really hibernation; more like a torpor.

By the end of winter, when they’re ready to emerge, a black bear may have lost more than one-fourth of its weight. While they emerge hungry, they have amazingly not lost their strength.

If you or I slept for four or five months, we’d not only have bed sores, our muscles would have withered away with atrophy.

Not bears.

Timmins has found denning bears in a state of minor shivering, like twitching, which may help keep their muscle mass. Other adaptations of their physiology let them retain their bone mass during the long winter nap.

Historically, New Hampshire’s black bears have emerged from their dens around late-March or early April, Timmins said. But increasingly, because of a trend of warmer winters, bears have been emerging by early or mid-March.

As you would emerge from such a long nap, you’d be famished and looking for a meal. Bears will often forage for remains of the previous fall’s acorns and beech nuts, the first foods readily available. That diet slowly shifts to grasses and forbs as spring progresses.

Meanwhile, as some of those males are still awake, Fish and Game reminds folks to keep the bird feeders put away until we get a solid snow or cold snap. Dec. 1 is a good rule of thumb.

Eric Aldrich writes from his home in Hancock. ericadine@gmail.com.