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Time to Leave the Dens

It’s that time of year again when a lot of our wildlife will begin leaving their winter homes along with their new additions.

One of the most obvious critters that has been absent from our very white and snowy winter landscape is the black bear. I’m sure that most people know that black bears den up over the winter months, but there may be some things that some folks are not aware of.

Like many other wild animals, bears will increase their feeding activity in the late fall months to fatten themselves up for the long winter of hibernation. When, exactly, they go into hibernation depends a lot on food availability, with poor food availability resulting in an earlier move to the den sites. Hibernation in bears is not actually a true hibernation, but it’s more like a “resting period” rather than a deep torpor state; while the heart rate and respiration slow some, the body temperature does not drastically fall.

During hibernation, bears remain alert and aware of their surroundings. I once encountered a large black bear in its den site under a large fallen dead tree; as I moved a bit closer for a photo, the bear looked up at me, and I quickly retreated. It’s also interesting to note that while bears are dormant in their den sites, they do not defecate or urinate.

Pregnant females usually den first, followed by males several weeks later. Males will den alone while pregnant females will also den alone and give birth while denned. Females, with their first-year cubs, den with their young.

A den, by the way, is not necessarily a cave, but it is more likely a hollow tree, a cavity under a large rock, a nest beneath the roots of a fallen tree, or even an open area on top of the ground in or near some brush. Bears line their dens with bark, grasses, and leaves.

Bears mate from early June to mid-July, and as I mentioned earlier, the cubs are born during early January while the female is still denned.

Years ago, when well-known biologist Gary Alt handled bear research for the Pennsylvania Game Commission, I had several opportunities to go with him when he extracted the newborn cubs from the den. Cubs were weighed, measured and tagged, and returned to the den.

Of course, mama bear had to be tranquilized first before crawling into the den to get the cubs. On one occasion, Gary “allowed” me to crawl 15 feet down the tunnel to retrieve the cubs — very exhilarating, to say the least.

The female and her cubs generally leave the den when the cubs are about three months old, which brings us to the present time on the calendar. By fall, those same cubs will weigh around 60 to 100 pounds and will stay with the mother bear until late fall when they again will den with the mother bear; following that, the family group disbands the coming spring.

Of course, now, in the days to come, the chances of spotting one of these family groups is a strong likelihood; spotting a larger bear running alone is likely a male.

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