The best habitat for black bears in Vermont is a mixture of coniferous trees, hardwoods, wetlands, and variation in terrain. Because they need dense cover to escape danger, the wary and elusive black bears prefer rough and wooded habitats. The habitat should also have a good water supply nearby.
Coniferous trees provide concealment and protection from severe weather. Stands of beech and oak, along with wetlands, are important feeding areas for bears in Vermont.
Bears are usually silent and travel alone. Exceptions are family groups and breeding adults during the mating season. Family groups typically consist of the adult female and her cubs, which travel with her through their second spring.
Black bears climb trees to feed on ripening fruit and as a means to escape danger. Bears will sit near the trunk of a tree on a large branch and pull other branches towards them to eat the nuts. This eating place looks like a large bird’s nest, with all the branches pulled toward the center. Bears climb trees with the use of their claws, and claw marks can usually be seen on the trunk.
Although bears are often thought to hibernate, they are not true hibernators. During true hibernation, body temperature, respiration, and metabolic rates are considerably decreased.
A bear’s respiration and metabolic rate do decrease during the winter sleep, but its temperature remains close to normal. Thus a bear in a winter den can be easily aroused within moments, whereas in a true hibernator, it may take several hours.
Food supplies are the most critical factor determining when bears den in the fall. When foods are abundant, bears will continue eating throughout the snows of November and into December. When fall foods are scarce, most bears den by mid-November.
The den is commonly a brush pile. It may also be a pocket or cave in rocky ledges; a hollow in a large tree or a fallen log; a sheltered depression or cavity dug out at the base of a log, tree, or upturned root; or even a simple hole dug into a hillside.
Male bears den up almost anywhere. Females, however, are more particular, selecting protected sites and lining them with stripped bark, leaves, grasses, ferns, or moss.
Bears become mature at about three and a half years. Black bears give birth every other year. The breeding season occurs during June and July.
After mating, the fertilized egg does not become placed into the mother’s uterus and grow until fall. This process is called “delayed implantation.” The egg will begin to grow only if the female has attained a minimum body weight of 150 pounds.
The female’s ability to produce cubs relates directly to fall food supplies. If the food supplies are poor prior to denning, the female may not have enough fat reserves to grow a cub, and so no cubs will be born.
Inadequate food supplies may also affect fetal development and cub survival. In most years, the cub mortality is around 20 percent, but may be as high as 50 percent during years of food scarcity. Well –nourished females are much more likely to produce healthier, larger cubs, and in greater numbers.
Cubs are born in late January or early February while the mother is denning. The number of cubs varies from one to five, but the average is two.
The cubs, weigh only 8 to 10 ounces at birth, and are about the size of a chipmunk. The cubs will remain with the mother until they are about 16 months old. Young females may remain close to their mother’s home range, but young males must find their own territory.
Although the black bear belongs to the order Carnivora, it is a true omnivore, eating both plants and animals. Major food sources include seeds and insects, but the black bear is an opportunist and will eat just about anything that crosses its path. Early spring is the most difficult time of the year for bears. At this time, food is scarce and bears must scavenge intensively to stay alive. Because wetlands green up first, wetland grasses and green, leafy plants have been found to be the primary food of the black bear in the spring. However, these have limited nutritional value, so bears continue to draw from any remaining fat reserves.
From the time they emerge from their dens to the end of July, their activities center around forested wetlands, beaver dams, and along streams and riverbanks.
Typically, bears must wait until early to mid-summer before regaining an adequate level of nutrition. By early summer, bears have the opportunity to eat a variety of succulent plants such as the roots of the jack-in-the-pulpit and berries that are beginning to become available. Bears may also prey upon young deer and moose at this time, although bears do not actively hunt for these food sources. During this time, no single food source is available in such abundance that bears can concentrate on only one item.
As summer progresses, raspberries, blueberries, and blackberries ripen. If these crops are abundant, bears immerse themselves in a concentrated food source with high sugar content.
By late August, bears seek foods with the highest nutritional value. In an effort to store as much energy as possible, they will eat up to 24 hours a day. If beechnuts and acorns are plentiful, bears will move into productive beech and oak stands and consume high quantities of the nuts. Bears may travel many miles to reach fall food supplies and will continue to forage for beechnuts for several weeks.
Other fall foods include cherries, apples, succulent plants, and berries. Bears will also eat available crops of corn and oats, and will commonly raid bee hives.