Behaviour and life history Bear

1 behaviour , life history

1.1 feeding
1.2 communication
1.3 reproduction , life cycle
1.4 hibernation
1.5 predators, parasites , pathogens

behaviour , life history

american black bear tracks

brown , american black bears diurnal, meaning active part during day, though may forage substantially night. other species may nocturnal, active @ night, though female sloth bears cubs may feed more @ daytime avoid competition conspecifics , nocturnal predators. bears overwhelmingly solitary , considered asocial of carnivora. times bears encountered in small groups mothers young or occasional seasonal bounties of rich food (such salmon runs). fights between males can occur , older individuals may have extensive scarring, suggests maintaining dominance can intense. acute sense of smell, bears can locate carcasses several kilometres away. use olfaction locate other foods, encounter mates, avoid rivals , recognise cubs.

feeding

giant panda feeding on bamboo. species entirely herbivorous.

most bears opportunistic omnivores , consume more plant animal matter. eat leaves, roots, , berries insects, carrion, fresh meat, , fish, , have digestive systems , teeth adapted such diet. @ extremes entirely herbivorous giant panda , carnivorous polar bear. however, bears feed on food source becomes seasonally available. example, asiatic black bears in taiwan consume large numbers of acorns when these common, , switch ungulates @ other times of year.

when foraging plants, bears choose eat them @ stage when @ nutritious , digestible, typically avoiding older grasses, sedges , leaves. hence, in more northern temperate areas, browsing , grazing more common in spring , later becomes more restricted. knowing when plants ripe eating learned behaviour. berries may foraged in bushes or @ tops of trees, , bears try maximize number of berries consumed versus foliage. in autumn, bear species forage large amounts of naturally fermented fruits, affects behaviour. smaller bears climb trees obtain mast (edible reproductive parts, such acorns). such masts can important diets of these species, , mast failures may result in long-range movements bears looking alternative food sources. brown bears, powerful digging abilities, commonly eat roots. panda s diet on 99% bamboo, of 30 different species. strong jaws adapted crushing tough stems of these plants, though prefer eat more nutritious leaves. bromeliads can make 50% of diet of spectacled bear, has strong jaws bite them open.

brown bear feeding on infrequent, predictable, salmon migrations

the sloth bear, though not specialised polar bears , panda, has lost several front teeth seen in bears, , developed long, suctioning tongue feed on ants, termites, , other burrowing insects favour. @ times of year, these insects can make 90% of diets. species may raid nests of wasps , bees honey , immature insects, in spite of stinging adults. sun bears use long tongues lick both insects , honey. fish important source of food species, , brown bears in particular gather in large numbers @ salmon runs. typically, bear plunges water , seizes fish jaws or front paws. preferred parts eat brain , eggs. small burrowing mammals rodents may dug out , eaten.

the brown bear , both species of black bears take large ungulates, such deer , bovids, young , weak. these animals may taken short rush , ambush, though hiding young may stiffed out , pounced on. polar bear preys on seals, stalking them ice or breaking dens. eat highly digestible blubber. large mammalian prey typically killed bite head or neck, or (in case of young) pinned down , mauled. predatory behaviour in bears typically taught young mother.

bears prolific scavengers , kleptoparasites, stealing food caches rodents, , carcasses other predators. hibernating species, weight gain important provides nourishment during winter dormancy. brown bear can eat 41 kg (90 lb) of food , gain 2–3 kg (4.4–6.6 lb) of fat day prior entering den.

communication

asian black bears during aggressive encounter

bears produce number of vocal , non-vocal sounds. tongue-clicking, grunting or chuffing many made in cordial situations, such between mothers , cubs or courting couples, while moaning, huffing, sorting or blowing air made when individual stressed. barking produced during times of alarm, excitement or give away animal s position. warning sounds include jaw-clicking , lip-popping, while teeth-chatters, bellows, growls, roars , pulsing sounds made in aggressive encounters. cubs may squeal, bawl, bleat or scream when in distress , make motor-like humming when comfortable or nursing.

sloth bear rubbing against tree

bears communicate visual displays such standing upright, exaggerates individual s size. chest markings of species may add intimidating display. staring aggressive act , facial markings of spectacled bears , giant pandas may draw attention eyes during agonistic encounters. individuals may approach each other stiff-legged walking head lowered. dominance between bears asserted making frontal orientation, showing canine teeth, muzzle twisting , neck stretching. subordinate may respond lateral orientation, turning away , dropping head , sitting or lying down.

bears may mark territory rubbing against trees , other objects may serve spread scent. accompanied clawing , biting object. bark may spread around draw attention marking post. pandas known mark objects urine , waxy substance anal glands. polar bears leave behind scent in tracks allow individuals keep track of 1 in vast arctic wilderness.

reproduction , life cycle

american black bears mating

the mating system of bears has variously been described form of polygyny, promiscuity , serial monogamy. during breeding season, males take notice of females in vicinity , females become more tolerant of males. male bear may visit female continuously on period of several days or weeks, depending on species, test reproductive state. during time period, males try prevent rivals interacting mate. courtship may brief, although in asian species, courting pairs may engage in wrestling, hugging, mock fighting , vocalising. ovulation induced mating, can last 30 minutes depending on species.

polar bear mother nursing cub

gestation typically lasts 6–9 months, including delayed implantation, , litter size numbers 4 cubs. giant pandas may give birth twins can suckle 1 young , other left die. in northern living species, birth takes place during winter dormancy. cubs born blind , helpless @ thin layer of hair, relying on mother warmth. milk of female bear rich in fat , antibodies , cubs may suckle year after born. 2–3 months, cubs can follow mother outside den. follow on foot, sloth bear cubs may ride on mother s back. male bears play no role in raising young. infanticide, adult male kills cubs of another, has been recorded in polar bears, brown bears , american black bears not in other species. males kill young bring female oestrus. cubs may flee , mother defends them @ cost of life.

in species, offspring may become independent around next spring, through may stay until female mates again. bears reach sexual maturity shortly after disperse; @ around 3–6 years depending on species. male alaskan brown bears , polar bears may continue grow until 11 years old. lifespan may vary between species. brown bear can live average of 25 years.

hibernation

bears of northern regions, including american black bear , grizzly bear, hibernate in winter. during hibernation, bear s metabolism slows down, body temperature decreases slightly, , heart rate slows normal value of 55 9 beats per minute. bears not wake during hibernation, , can go entire period without eating, drinking, urinating, or defecating. fecal plug formed in colon, , expelled when bear wakes in spring. if have stored enough body fat, muscles remain in condition, , protein maintenance requirements met recycling waste urea. female bears give birth during hibernation period, , roused when doing so.

predators, parasites , pathogens

hunters shot bear, sweden, 20th century

as animals @ summit of food chain, bears not have many predators. important humans, , started cultivating crops, increasingly came in conflict bears raided them. since invention of firearms, people have been able kill bears greater ease. tiger four-legged predator regularly preys on adult bears, including brown bears, sloth bears, asiatic black bears, , sun bears.

bears parasitized eighty species of parasites, including single-celled protozoans , gastro-intestinal worms, , nematodes , flukes in heart, liver, lungs , bloodstream. externally have ticks, fleas , lice. study of american black bears found seventeen species of endoparasite including protozoan sarcocystis, parasitic worm diphyllobothrium mansonoides, , nematodes dirofilaria immitis, capillaria aerophila, physaloptera sp., strongyloides sp. , others. of these, d. mansonoides , adult c. aerophila causing pathological symptoms. contrast, polar bears have few parasites; many parasitic species need secondary, terrestrial, host, , polar bear s life style such few alternative hosts exist in environment. protozoan toxoplasma gondii has been found in polar bears, , nematode trichinella nativa can cause serious infection , decline in older polar bears. bears in north america infected morbillivirus similar canine distemper virus. susceptible infectious canine hepatitis (cav-1), free-living black bears dying rapidly of encephalitis , hepatitis.