Bears and Other Carnivores

BEARS AND OTHER CARNIVORES Lynn Rogers The movements of carnivores are governed largely by the movements of their prey, and the need to find living areas away from where they were born. When food supplies fail, certain carnivores, particularly bears, travel great distances in search of nourishment, before returning home. A young male timber wolf (Canis lupus) foods. Most members of the order Carnivora, suddenly moves 886 kilometers (550 miles) however, are one step removed from this away from its lifelong range. A young female process, in that their movements are dictated lynx (Lynx canadensis) moves 483 kilometers primarily by the movements of their prey. The (300 miles) away from a place that usually most common prey of mammalian predators abounds with snowshoe hares. An 11-year-old are relatively sedentary mammals, reptiles, male black bear {Ursus americanus) moves amphibians, fish, invertebrates, and ground- 200 kilometers (125 miles) outside his home dwelling birds, with nesting waterfowl and area, but returns two months later. These are other seasonally migrant birds sometimes unusual movements for animals that generally giving a seasonal dietary boost. live in areas less than 40 kilometers (25 Since most prey species do not show miles) in diameter, but with the aid of seasonal migrations, neither do most radiotelemetry such movements are being carnivores. Exceptions are wolves, lions revealed more and more frequently. (Panthera leo), and other carnivores whose Modern studies have given new insights survival in some locations depends upon into the travels and capabilities of bears and seasonally migratory prey like caribou, elk, other carnivores. Their long-range movements bison, and African antelopes. usually fall into one of three categories. They Arctic wolf packs (Canis lupus tundarum) are either annual migrations to hunting or follow migrating caribou hundreds of feeding areas, unusual movements in years of kilometers, and the wolves that formerly widespread food failures, or permanent occupied the great plains of North America migrations to new living areas. probably followed nomadic herds of bison just as some tribes of Indians did. Lions that ANNUAL MIGRATIONS TO HUNTING OR FEEDING AREAS live on less mobile prey remain within home Annual migration for most animals involves ranges of 25 to 400 square kilometers (10 to movements to feeding or breeding sites, and 155 square miles), but other lions, mostly is usually tied to changes in season and to the males, follow migrating herds of wildebeest availability of plant or invertebrate animal and other herbivores of the African plains, moving up to 13 kilometers (8 miles) per day. primarily males without parental Spotted hyenas (Crocuta crocuta) are also responsibilities that follow the herds of flexible in their migratory habits. Of those migrating herbivores. studied on the Serengeti Plains, some Migrations by carnivores tend to be less established territories, some followed predictable than migrations by herbivores and migratory wildebeest and some commuted up birds because carnivores are less directly tied to 80 kilometers (50 miles) from their dens to to the seasonal cycle of plant growth and wherever the main concentrations of game insect abundance. Black bears are most likely were at the time. In other parts of the world, to show regular seasonal migrations' because mountain lions (Felis concolor), snow they are omnivorous, feeding on vegetation in leopards (Panthera uncia), and other spring, berries and nuts in the summer and mountain-dwelling predators follow prey to autumn, and to some extent on flesh and high elevations in summer and to low insects. But migrations even by black bears elevations in winter. are unpredictable and local, depending upon Carnivores that live in harsh climates are local food distribution and individual well adapted for the weather. Wolves, foxes, knowledge of distant food sources lynxes, Siberian tigers (Panthera tigris Bear migrations are by individuals, or by altaica) and others endure extreme cold by mothers and cubs, and not by large groups. growing thick winter pelts. Some of these Loose gatherings of competing bears may animals burrow under the snow for extra form where there is plenty of food, and in fact protection in the worst weather. Others, like the closest associations between black bears black bears, grizzly bears (Ursus arctos), are seen where food is most abundant. At skunks (Mephitis mephitis), and badgers garbage dumps bears sometimes feed less (Taxidea taxus) reduce their metabolisms to than a meter (3 feet) apart and some bears varying degrees and spend their winters find partners to wrestle and play with. In mostly underground, hibernating. The same natural feeding areas, where food is less animals withstand summer heat by shedding plentiful, bears usually stay more than 100 their underfur and seeking shade, water, or meters (330 feet) apart, even in places well cool burrows. In Arctic summers, polar bears known for black bears. One such place is (Thalarctos maritimus) sometimes burrow Mukwonago (derived from the Indian words down to the permafrost in order to cool off. mukwa, bear and onohko, fat), in Wisconsin, Seasonally migrant carnivores must have a which was famous for the large number of sedentary period in which to raise their bears that gathered to eat acorns in the white young. At birth, their offspring have their oak stands of that area in the early 1800s. eyes closed and are unable to walk, and they Indians and white men would converge on the require several weeks or months of intensive area from considerable distances to hunt the parental protection and feeding before they bears—a migration of human predators. can travel. In contrast, the mobile animals on Along the north shore of Lake Superior, which these carnivores prey give birth to food is most plentiful inland in early summer, young that can follow a herd within a few and near the shore in late summer and days of birth. In some species, like the lions autumn. Some of the inland bears were radio- of the Serengeti Plains of Africa, it is collared and followed to learn whether they explored outside their usual living areas and November 1974, during an invasion, moved found the richer food supplies near the shore 483 kilometers (300 miles) northwest into in season. Forty percent of 105 females d 69 Canada, where she was caught on 20 January percent of 32 males left their usual ranges 1977. Her movement is the longest on record each year, on the average, and foraged 7 to 92 for a lynx. The next longest movement kilometers (4 to 57 miles) away, sometimes recorded was for a male that lost a foot and abandoning abundant food at me. Not all the was nursed back to health in captivity. By the trips were pure exploration. Some of the bears time he recovered, another male had moved had learned the food-rich area near the shore into his former territory. The homeless lynx from their mothers and returned to it as then wandered on three legs until he was shot independent adults. Seventy percent of the raiding a farmer's poultry an astonishing 164 trips were to that area. One mother had found kilometers (100 miles) away. an oak stand near the shore, 30 kilometers (18 Migrating black bears have been making 1/2 miles) outside her territory, and led litter news in eastern North America for more than after litter to it over the years. She and her a century. These migrations differ from the cubs fattened on acorns in years when more more regular, shorter migrations made by sedentary bears were without this food. The bears visiting known feeding areas or cubs returned to the stand in subsequent years exploring the region surrounding their and became the fastest growing, earliest territories. In years when there is widespread maturing bears in the study area, their clan failure of berry, nut, and acorn crops, starving reproducing more rapidly than the sedentary black bears may leave a region in large clans. numbers and move to an area that is ecologically different. Black bears in northern FORCED MOVEMENTS forests can move into temperate deciduous In years when there has been widespread forest regions or even beyond, to the prairie failure of their normal foods, starving edge. Today, prairies have mostly been carnivores have made spectacular journeys. converted into farms and cities, and when a Canadian lynxes are noted for their southward bear moves to the suburbs of Minneapolis it is migrations during years when snowshoe hare likely to be killed. The same was true in the numbers are low in their usual range. Lynxes 1880s when waves of bears moved through are seldom seen in the United States, but populated areas. In years of mass movements, during these years they become common in bears were commonly found along water northern Minnesota and are seen occasionally barriers such as the Atlantic Ocean, the as far south as Minneapolis, more than 400 Mississippi River, and the Great Lakes. They kilometers (250 miles) south of the Canadian moved along the shorelines until they border. Lynxes fresh from Canada are seen encountered cities, where they were often crossing roads, watching traffic from the killed. Bears are still found on a few of these roadside, and moving through people's yards. old migration routes. For example, 160 black After a year or so the lynxes disappear, either bears were killed in 1985 on one such route because they have been trapped, shot, or on the outskirts of Duluth and Thunder Bay, killed on the roads, or they have returned to both cities on the north shore of Lake the forests of Canada. A young adult female Superior. lynx that was ear-tagged in Minnesota on 5 PERMANENT MOVES TO NEW adjacent to their parents' territories, three (two LIVING AREAS males and one female) moved more than 190 Many young mammals leave their birthplaces kilometers (120 miles), and three (two males for good before breeding.

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