American Black Bear (Ursa americana Pallas)
From: Saunders, D. A. 1988. Adirondack Mammals. State University of New York, College of Environmental Science and Forestry. 216pp. and Sage, R.W., Jr., and S. Simek. 1994. Adirondack Black Bears. State University of New York, College of Environmental Science and Forestry, Environmental Information Series.
Description: Shaggy black fur and large size distinguish this animal from all other Adirondack mammals. The black bear has a short, inconspicuous tail. The body and legs are short. The head is broad with erect, rounded ears. The muzzle, grizzled with brown, is long and narrow. The eyes are small and dark. Both front and hind feet have five toes, each with a large claw. A white blaze is often present on the throat or chest. Color phases occur but are uncommon in eastern populations. Adults are approximately 50 -78 inches in length. Average-sized adult males weigh 300 lbs. and females 150 lbs.
Range and Habitat: The black bear once occurred over most of North America from Alaska and Canada south into the central regions of northern Mexico, but now it is absent from parts of the central and north central U.S. The black bear occurred throughout the Adirondack Park in all terrestrial communities, and at all elevations, but is most abundant in the wilder areas of the Park. The annual harvest by bear hunters with in the Park averages 500-600. The black bear prefers dense, secluded forests. Mixtures of forest openings with luxuriant raspberry or blackberry plants and old-growth timber providing mast (acorns, beechnuts) and dens, affords ideal habitat.
Food Habits: Adirondack black bears eat a wide variety of foods. Approximately 90 percent of their diet is plant material consisting of not less than 30 different plant species. The remainder is primarily insects, but bears also will scavenge carcasses of larger animals, an, if the opportunity arises, prey upon live white-tailed deer fawns, small woodland mammals, and beaver. Bears are very will adapted for finding and gathering food. They have a keen sense of smell, powerful forearms, long claws, tremendous endurance, and are adept with their tongue and paws. As a result, black bears can dig out plant tubers or small rodents, tear apart rotten logs to find grubs, climb trees and break off branches to gather nuts, "pick" raspberries and blueberries, and travel long distances in search of new food resources.
In spite of their large size and tremendous strength, most items bears eat are small, and as a result a bear has to eat a lot at one sitting. It is not uncommon for bears to gorge themselves on a particular berry species for several days, or even weeks, eating virtually nothing else before moving on to another location or a different food resource. Although generally solitary animals (except for females with young), several bears may congregate in a localized area of high food abundance for short periods of time.
Black bears are very much in tune with their surroundings. Seasonal changes in the plant community result in varied food availability for bears. When bears emerge from their winter dens in early April, it takes a couple of weeks for their digestive system to "start-up" again after being shutdown all winter. Food is scarce in spring; there are no ripe berries or nuts as yet.
By mid-novemeber food resources are becoming scarce and the Adirondack black bears, now fattened for winter, begin to seek out a favorable den site. Feeding activity has nearly ceased and the bears' metabolic rate begins to slow in preparation for winter hibernation. Pregnant females are usually the first to enter their dens followed by barren females and then males. By Thanksgiving most Adirondack black bears are secure in their dens waiting out the long winter.
Food abundance and diversity is a critical part of Adirondack black bear habitat. Food availability also plays a key role in population dynamics. Lack of adequate food resources has been shown to have a direct negative effect on female reproductive rates, age of maturity, survival of young, and growth. Indirectly, food resource limitations in the wild can lead to increased bear/human interactions. Some hungry bears will seek out landfills, garbage cans, or public campsites as alternative sources of food. Many humans are intolerant of bears around their homes and camps, and the bear is usually the loser in any confrontation. Feeding bears acclimates them towards humans and their surroundings, increasing the potential of nuisance bear problems. Removal of excessive numbers of nuisance bears can have a negative impact on the population.
Public lands within the Park, protected under the state constitution from development and timber harvesting, often support mature forests dominated by shade tolerant species such as beech. Large mature trees provide abundant fruit/nut crops. Over mature and fallen trees harbor insects and small mammals. In contract, a large segment of the privately-owned land within the Adirondack Park is actively managed for timber production and/or a wide variety of outdoor recreational activities. The pulp and wood products from New York's lands are used by all of us on a daily basis. Timber harvesting results in the periodic removal of trees from forest stands according to a prescribed management plan designed to perpetuate timber production on a sustained basis. Such harvesting creates openings in the forest canopy which encourages growth of light-loving plant species, such as raspberry, blackberry, pin cherry, aspen, scarlet elder, and black cherry as well as a variety of shade tolerant plants and trees. Well-planned timer management programs result in a variety of tree age classes ranging from young seedlings and saplings to mature trees. Furthermore, such practices promote the establishment and development of a diverse plant community which includes intolerant, mid-tolerant and shade tolerant woody and herbaceous plants.
Research conducted through the AEC on black bear food habits and habitat use in the central Adirondacks has shown that raspberry abundance is 48 times higher, and pin cherry production is 37 times higher, on managed private timberlands when compared with unmanaged public Park land. Although beechnut production was greater on unmanaged lands within the Park, managed timber stands also produced high numbers of beechnuts, and greater numbers of juneberries, elderberries, and blackberries. During the spring and summer bears preferred managed timberlands over unmanaged lands. Bears used managed and unmanaged lands equally during the fall. Wetland areas and fire succession stands found on both private and public lands within the Park were also important food production areas used by bears periodically during the spring, summer, and fall.
The interspersion of relatively large tracks of forested managed and unmanaged land throughout the Adirondack Park provides for continued production of the wide range of food resources important to black bears during all seasons of the year. Together these two forest landscapes assure the continuation of the diversity of habitats necessary to support a thriving black bear population in the Adirondacks. New York state's black bear population in the third largest in the eastern United States.
Activity and Movement: During the warmer months of the year, a black bear leaves its day bed, a shallow depression on the ground, in late afternoon or at dusk, and may remain active throughout the night. Feeding or breeding activity may take place during daylight hours as well.
The black bear spend the winter months in a den where it enters into a deep sleep. Although not a true hibernator, the bear's body temperature declines 10 degrees F and their metabolic rate declines 50-60%. During this period of dormancy, a black bear does not eat, drink, urinate, or defect, and relies upon fat reserves for energy, losing approzimately15-25 % of its body weight. Photo period (day length) and food availability rather than temperature or other weather factors appear to cause bears to enter winter dens. Females tend to den earlier (usually by late November) than males (mid December). Emergence is in the reverse order, and occurs in late March and early April. Den sites include cavities within of under rocks, hollow trees, brush piles, fir and spruce trees, wind-toppled trees, and rarely in open areas of forest floors that offer no protection other than a blanket of snow.
When traveling on the ground, the black bear often uses the same pathway or trail, sometimes stepping in the same footprints for years. The normal gait is a deliberate, slow walk, sometimes punctuated with pauses during which the bear stands on its hind limbs to sniff the air or perhaps have a better view. Bears bound or gallop when running, and can attain speeds of 28-32 mph for brief periods. The black bear may wade or wallow in mud or water, and is a strong swimmer, capable of swimming at least 5 miles. This mammal climbs trees by pulling itself up with its front legs and it backs down tree trunks
The black bear is very mobile, often traveling several to many miles in one night. Evidence of this mobility stems from documented wanderings of translocated individuals. One male moved 259 miles after its release. Another, captured in the Adirondacks and released on Tug Hill, returned 56 miles to the point of capture. This ability to move long distances shows that capture-transfer programs for nuisance bears are futile; they either become a problem bear in another community, or return to their original location.
Reproduction: Black bears mate in June and July. Adult females breed every other year. If a female's cubs succumb before the breeding season, she may mate that same year and produce cubs the following year. The gestation period is 225 days. However, most embryonic development is during the last 6-8 weeks of pregnancy. A female gives birth to her litter of 1-6 (average 2) young in January or February in the winter den. At birth, the cubs are blind, weigh 6-12 oz, and are covered with fine-textured gray hair. Their eyes open at 4-6 weeks of age. They leave the den when about two months old, but continue to nurse for another 5 months. Black bear cubs stay with the female until the following spring. Throughout this period, the female is intolerant of intruders, and may defend her cubs with ferocious, aggressive behavior (one of several reasons why it is unwise for humans to approach the species). Black bears are sexually mature at 3.5-7.5 years. Forty-one years is the oldest known age for an Adirondack bear; few live more than 10 years.
Predators: The black bear has no predators among the wild animals that currently reside in the Adirondack Park except other black bears. This species is cannibalistic under certain conditions.
Social System - Comparatively little is known about the mating system and social organization of the black bear. This is especially true for the Adirondack population. This species is thought to be promiscuous, and with the exception of the family unit, is solitary except when breeding or congregating around landfills or campsites.
Age, sex, season, and population density are important determinants of home range size. Home ranges overlap; males have larger (100-125 sq. mi) ranges that females (24-50 sq. mi). North American densities vary from one black bear per 0.9 - 76 sq. mi.
Communication - Although usually silent, bears vocalize in social contexts and aggressive encounters with other species (woofs, roars, grunts, moans). Cubs whimper, squeal, and purr. Combinations of vocal and visual (motor patterns, displays involving ear positions and facial expressions) signals are prevalent in dominant-subordinate conflicts that occasionally progress to fighting. Black bears mark trees, biting and clawing trunks 5-7 ft above the ground. On smooth barked trees such as beech, scars from marking as well as from climbing, are visible for years. The function of tree marking is unknown, but may be a form of signaling.
Costello, C. 1992. Black bear habitat ecology in the central Adirondacks as related to food abundance and forest management. M.S. Thesis. State University of New York, College of Environmental Science and Forestry, Syracuse, 165 pp.
O'Pezio, J. 1984. Unraveling the mysteries of bear denning. The New York State Conservationist, 38(4):23-25.
Sauer, P.R., L. Free, and S.D. Browne. 1969. Movements of tagged black bears in the Adirondacks. New York Fish and Game Journal, 16:205-223.
Simek, S.L. 1995. Impacts of forest land management on black bear populations in the central Adirondacks. M.S. Thesis, State University of New York, College of Environmental Science and Forestry, Syracuse, 232 pp.
Tietje, W. D., B.O. Pelchat, and R.L. Ruff. 1986. Cannibalism of denned black bears. Journal of Mammalogy, 67:762-766.