Black Bear Research Paper

Age and Sex Specific Seasonal Variations in Weight of Black Bears in Pakistan Bears Sanctuary

Little is known about the natural ecology and behavior of the Asiatic bear. Their diet varies depending on the season but, in common with most other bears, they are predominately herbivorous feeding on acorns, beech and other nuts as well as fruits and berries (Burnie,D. 2001). These bears spend around half of their time in the trees (Animal Diversity Web, July 2002) and construct platforms from branches and vegetation upon which they rest and feed (IUCN/SSC Bear and Polar Bear Specialist Group 1998). Females give birth to a litter of around 2 cubs in the safety of a winter den (Burnie, D. 2001). It often located within a tree hollow (IUCN/SSC Bear

and Polar Bear Specialist Group 1998). Cubs stay with their mother for 1 to 1.5 years but, with the exception of these groupings, Asiatic black bears are fairly solitary (Animal Diversity Web July, 2002).

At the northern extreme of its range, black bears may go into hibernation to survive the cold winters, although further to the south, bears migrate to warmer areas and thus avoid the need for hibernation (Animal Diversity Web July, 2002).

Hibernation

Denning and hibernation among black bears varies with latitude, from 5 to 7 months in northern Canada and Alaska to a week or so in northern Mexico. In areas with mild climates, bears may den for 3 to 4 months. However, some bears–particularly males–may remain active all or most of the winter, especially in mild or snow-free years. In one Massachusetts study, bears denned for about 4 months in 1980-81 and about 5 months in 1981-82. Several studies have concluded that den entry is dependent on fall food supply. Bears remain active longer when food is abundant, but enter the den earlier when food is scarce and fruitless searching results in a negative energy balance. However, gravid females may den as soon as they have accrued sufficient fat reserves for reproduction. The cumulative effects of increasing precipitation and lower temperatures may also play a role in the onset of denning. In Ontario, den entry dates ranged between September 20 to November 29 over a 5-year period,

while in Tennessee 83% of bears entered between December 25 and January 7. In Massachusetts, den entry varied between November 8 and December 3 over a 3-year period. Maine bears showed an alternating pattern, denning in October when beechnuts were scarce and in November when they were abundant. Den entry by sex and age class is variable throughout North America. In Maine and Ontario, pregnant females denned before females with yearlings while the opposite was true in New York. Males generally entered dens last. In one Massachusetts study, the sequence was barren females, pregnant females, males, and females with yearlings, all of which denned within 8 to 10 days of each other. Males are typically the first to emerge from the den and females with newborn cubs the last. Males emerged in late March in New York, with sow-cub groupings in mid-April. In boreal areas in Montana and Ontario, some females with cubs remained denned until early May. Den emergence is probably timed to coincide with snow melt (as in Maine) and with the availability of spring foods. In Massachusetts, bears emerged during the first week of April in a warm spring, but between April 19 and May 1 after a late spring snowfall. In Minnesota, temperatures of 50º F or more for 2 to 4 days stimulated den emergence. (Elowe et al., 1984)
Good Climber
Black bears undoubtedly evolved as forest animals and are rarely found far from trees.

They are excellent climbers and easily ascend trees by hooking or gripping them with their short, narrow claws. Cubs are capable of climbing as soon as they exit their natal den and readily climb in response to intrusion by strange bears or humans. The sow does not need to signal the cubs to climb, although she may readily do so. Cubs can easily climb to 100 feet or more. Black bears of all ages retain the climbing ability, although some old, large males may be reluctant to do so. The bears climb not only to escape a threat but also to rest, sleep, play, nurse, obtain food, or attain shelter (Bray and Barnes, 1967)

Good Swimmer

Black bears are also good swimmers and do not hesitate to enter water, whether to cross a waterway or to bathe or wallow. Two bears translocated to a small island in Newfoundland swam at least 0.6 mile through salt water to return to the capture site. Bears have also been seen swimming in Yellowstone Lake, Wyoming, “miles from shore”. In Massachusetts, bears regularly swim across the Connecticut River. (Bray and Barnes, 1967)

Diseases affect the health of black

bear
Wildlife diseases do not appear to play a major role in morbidity and mortality of black bear populations. However, routine surveillance is lacking. Bears in Idaho showed antibodies for tularemia (19%), Q-fever (6%), brucellosis (5%), leptospirosis (1%), and other pathogens but none showed serious clinical signs of the diseases. In the Great Smoky Mountains National Park, bears showed antibodies for Leptospira sp. (22%), but tested negative for brucellosis and canine distemper. Bears sometimes show evidence of periodontal disease and dental caries (“cavities”). Black bears rarely contract rabies. Large amounts of virus are necessary to infect the animal and infected individuals show little or no virus in their saliva. Only 10 rabid bears were reported in North America through 1983. Since the onset of raccoon-strain rabies in the Northeast, 1 rabid bear has been reported in New York and none in Massachusetts. Captive or pet bears may be a greater risk. In Iowa, a captive cub at a petting zoo developed acute neurologic signs and died. Initially diagnosed with rabies (but later proved to be false-positive), the animal exposed an estimated 350 persons from 10 states. The initial expense to contact these people and give them post-exposure treatment was substantial.( Binninger et al. 1980, Cook and Pelton 1978, Gleason et al. 1999, Rogers 1983)