By Neal Lineback and Mandy Lineback Gritzner, Geography in the NewsTM and Maps.com
THE GRIZZLIES’ TERRITORY IS CONTRACTING
At the end of July, 2010, a female grizzly bear with her three cubs in tow attacked three different tents near Yellowstone National Park in Montana. The middle-of-the-night maulings, the most brazen attacks in the area since the 1980s, left one camper dead and two others injured. Now investigators want to know why the sow stalked and attacked the humans for no apparent reason. There have been several maulings by grizzlies in and around Yellowstone in recent years and one death, leading rangers to recommend bear spray (large containers of pepper spray) to be carried by hikers in the Yellowstone back country.
Very different from the more common and smaller black bear (Urus americanus), the grizzly bear (Urus arctos horribilis) is actually a subspecies of brown bear (Urus arctos). The bear is named for the long white-tipped guard hairs on its back and shoulders, which give it a “grizzled” appearance. The grizzly generally inhabits the highlands of western North America and is the only brown bear found in the lower 48 states.
Biologists believe the grizzly subspecies descended from the Ussuri brown bear of Asia. The Ussuri crossed from Eastern Russia to Alaska via the Bering Strait land bridge 100,000 years ago. However, they did not move southward until 13,000 years ago.
The North American grizzly bear lives in a variety of habitats, including arctic tundra, dense forests and subalpine meadows. In the continental United States, about 1,000 grizzlies reside in the Rocky Mountains of Idaho, Montana, Washington and Wyoming. Approximately 25,000 grizzlies live in western Canada and another 30,000 in Alaska.
Throughout its geographic extent, the grizzly is protected by law. In the wild lands of Canada and Alaska, however, grizzlies are hunted legally as big game trophies.
Combining the United States and Canada, grizzly bears inhabit approximately half the area of their historical range. They were once found from Alaska to Mexico, even roaming the Great Plains. When Europeans began to settle the country, however, human encroachment pushed grizzly populations higher into the mountains and into more isolated forests.
Grizzlies are normally quite solitary predators. They are omnivorous, eating both plants and animals. Plants make up 80-90 percent of their diet, with numerous berries comprising a large portion of this. Grizzlies are opportunists, preying on both small and large mammals including moose, elk and caribou. Grizzly bears also eat fish, particularly including salmon and trout when available. They will scavenge food, including carrion left by other animals. A grizzly’s diet changes depending on what is available in the season.
Hibernating during the winter for 5-8 months, grizzlies eat heartily in the summer and fall preparing for hibernation. They must build up large fat reserves to ensure survival during the denning period.
Adult grizzly bears are large, but their size generally depends upon geographic location and the food available to them. An adult male weighs between 300-850 pounds (136-386 kg) and a female weighs 200-450 pounds (91-204 kg).
Every other year, females (sows) birth one to four young (most commonly two). The cubs are born small, weighing only about one pound (450 grams). The mother nurses the cubs to about 20 pounds (9 kg) before they emerge from the den in the spring. Very protective of her cubs, a mother grizzly will attack if she believes she or her cubs are threatened.
Humans cause the biggest threats to grizzly bears. As more people inhabit or visit those areas where grizzlies live, interaction becomes almost inevitable. Once a grizzly has become habituated to human food or has attacked a human, the animal may have to be euthanized as it becomes more aggressive.
Furthermore, climate change appears to be affecting grizzly bears’ range. The white bark pine, whose seeds are a very important natural source of food for grizzlies, is on the decline. Increased drought conditions and warmer temperatures are leading to white pine blister rust and pine beetle outbreaks that are killing white pines in many areas. As white pine seeds wane, grizzlies are forced to descend to lower elevations to search for food. Unfortunately, this often brings them in closer contact with humans.
Although grizzlies normally prefer to stay far from humans, it does pay to be aware while in grizzly territory. Whistling, ringing a bell or clapping while hiking is recommended as a warning to any grizzlies, usually sufficient to cause them to leave the area.
Unfortunately, the people attacked in the 2010 incident near Yellowstone never even knew the grizzly sow and her cubs were nearby. As it turns out, biologists found the cubs to be slightly malnourished. Strangely enough, though, investigators found no food in the tents of the people who were mauled, so the grizzly apparently was not attracted to human food. The sow was within the normal weight range and biologists remain baffled by the attacks. The sow was euthanized and her cubs were sent to a zoo.
In other incidents, hikers surprised a mother grizzly and her cubs, leading to a confrontation and the death of one person inside Yellowstone National Park in 2011. Such surprises can lead to tragedies.
Of all bears, the grizzly bear and the polar bear can be the most aggressive, given the right circumstances. Avoidance is the best way to prevent a confrontation with either.
And that is Geography in the News™.
This is a revised version of GITN 1056 (Aug. 27, 2010), rewritten for David Braun’s NGS NewsWatch post. Nearly 900 of the 1200, full-length weekly Geography in the News articles (with Spanish translations) are available in the K-12 online education resource Maps101.com, including maps and other supporting materials and critical thinking questions.