Brown Bears in ANWR
Grizzly Bears of the Arctic National Wildlife Refuge
The magnificent and solitary brown bear of Alaska's Arctic National Wildlife Refuge is well suited to life in the far north.
The Arctic National Wildlife Refuge is best known for the controversy surrounding oil development and the vast herds of caribou that calve on the coastal plain every summer. However the refuge is also home to many remarkable animals adapted to Arctic living, including the titan of the tundra, the brown bear.
Brown Bear or Grizzly Bears?
The names brown bear and grizzly bear are both used in Alaska to describe the same species: Ursus arctos. The bear’s name, feeding habits and size vary somewhat with geography, but generally the bears found near coastal areas are called brown bears, while the inland bears are called grizzlies. The brown bears in ANWR live further north, and are smaller than any others of members of their species.
Diet of the Brown Bear
The Alaska Department of Fish and Game researchers have found that the brown bear’s diet is roughly 55% plants, such as sedges, roots, berries, grasses and other non-woody plants. The remainder of their diet is comprised of lemmings, ground squirrels, grubs, and carcasses (mainly of caribou). In the spring, particularly if a mother bear has cubs to feed, she will prey on the newborn calves of caribou and moose.
Hibernation or Winter Sleep?
Climatic conditions in ANWR are harsh and the growing season short; bears must forage over vast tracks of tundra to find food and build adequate fat reserves for a winter hibernation lasting nearly eight months. For years scientists have debated whether bears experience a true hibernation or simply a deep sleep. A recent study published in the October 15, 2003 issue of The Journal of the American Veterinary Medical Association, reports that hibernating bears have a significantly reduced heart rate, along with other physiological changes that lend weight to the argument in favor of true hibernation.
Slow Reproduction Rates
During hibernation bears do not eat, drink, urinate or defecate, but they do give birth to small naked cubs weighing less than a pound each. The cubs (usually two) nurse and develop during their mother’s hibernation, then emerge from the den with her in the spring. Brown bears have one of the lowest reproduction rates of any terrestrial animal. Typically a female does not reproduce until she is four to six years old, then remains with her cubs for two to three years before being ready to breed again. During her twenty or so years of life, she may only have four to six pairs of cubs.
Need Vast Undeveloped Habitat
Unlike black bears who have adapted to living close to human activity, the brown bear is a true wilderness animal. It can only survive on vast tracts of wild lands, far from human development in places like The Arctic National Wildlife Refuge.
To read more about the Arctic National Wildlife Refuge see:
