Here's da bear facts!

[Lee Borgersen]

                        The mystery of Minnesota's black bears.

 Feb 17, 2015


 
 








It won't be long and it will be springtime. Already mid-February, hibernating mammals throughout the northland will eventually emerge from their underground sleeping chambers.







Some of the true hibernators, such as chipmunks, 13-lined ground squirrels and woodchucks, might have already stirred deep inside their burrows, but have likely not taken a peek outside as of yet.

American black bears, on the other hand, which are not considered true hibernators, will be ambling about the forests and woodlands in search for food before the hibernating ground squirrels arise. Indeed, late March and early April is the month of awakening for Minnesota's black bears. Having denned up several months ago — sometimes as early as September or as late as November — most black bears will have lost anywhere from 15 to 30 percent of their body weight by the time April rolls around.

Black bears are fascinating mammals that are fairly abundant across their range. And though sometimes becoming problematic for homeowners, farmers, and apiarists, especially when natural foods are scarce, black bears — sometimes called "black ghosts" of the forest — are

generally shy, elusive, and rarely observed.

While polar bears have been know to reach weights of more than 2,000 pounds and brown bears well more than 1,000 pounds, a 300-pound black bear is considered big. Even so, some male black bears routinely reach a weight of 500 to 600 pounds. There are even records of 700 and 800 pound bruins.

As I've already mentioned, black bears are not true hibernators. In fact, while all bears do indeed sleep the winter away with notable decreases in their vital signs, periodic arousal does occur. Moreover, female bears give birth to one to five cubs in January or February while "hibernating." The cubs nurse throughout the winter months as their mother mostly sleeps.

Choices of dens and den sites are highly variable from bear to bear, year to year, and location to location. Some bears will crawl into brush piles or within the tangles of deadfalls and root-wads to spend the winter months. Other bears will rake together plush nests of grasses and other vegetation underneath the boughs of evergreens to sleep away the wintertime. And some bears go underground when such luxuries are available or utilize the confines of a snug roadside culvert to curl up inside of. Some bears will den in the middle of unharvested cornfields or in the middle of cattails swamps. And believe it or not, one resourceful Wisconsin bear once used a bald eagle nest to hibernate in.

During the months of rest, black bears do not eat, drink, urinate or defecate — they survive solely on their fat reserves. Those reserves, which can amount to several inches thick inside their bodies, make up a substantial portion of a bear's overall weight. And because bears don't eat or drink during their winter snooze, little nitrogenous waste accumulates.

That withstanding, when black bears at last appear in the spring they will have lost a significant percentage of their bulk. Nursing females typically lose even more weight. It is for this reason that bears need to feed constantly on nutritious, high-protein and high-carbohydrate foods from early spring until late autumn. Their winter survival depends on it.

From April through the autumn months in woodlands across Minnesota, black bears will engage in a feeding binge of sorts. Bears need to gain as much weight as possible until they den-up again. Carrion is an important springtime food, as is the first new shoots of grass and other succulent forage — anything to maintain body weight.

However, as spring turns into summer and more diverse foods become available such as hazel nuts, acorns, berries, tubers, roots, herbs, grasses, and sedges, black bears begin putting on weight and accumulating fat. Animal matter, such as ants, grubs, beetles, small mammals and white-tailed deer fawns are also eaten. Even so, a black bear's diet generally consists of 75 percent plant material.

As summer wanes and fall approaches, weight-gains of up to 30 pounds per week are possible when good forage is available. When black bears do at last settle down for their long winter naps, a suitable den site is sought.

Upon a bear's emergence come springtime, the whole cycle of gaining weight starts again. Mating occurs in June through July and female black bears give birth seven or eight months later. The cubs are born very small, around eight ounces to a pound, and are blind, hairless and helpless. They will remain with their mother for at least a year, usually two, while learning many important lessons of survival.

The American black bear inspires many emotions to human admirers. They possess remarkable senses, and though they can grow large, they are quiet and quick. Extraordinarily powerful and intelligent, black bears are often misunderstood and needlessly feared. For sure, all of us are fortunate to have black bears roaming the forests as we get out and enjoy the great outdoors.