Grizzly Bear

Description

Grizzly Bear
Ursus arctos

Bears
Bear Family (Ursidae)

Measurement: Size: 180-220 cm/1 m at the shoulder Weight: 150-385 kg

Description: If there were one animal that all visitors to the Rockies hope to see (from the safety of their vehicle that is), it would be the Grizzly. Immense, powerful and uncommon, it symbolizes mountain wilderness. While experienced viewers can identify a grizzly without a thought, the uninitiated may confuse them with the more common black bear. Grizzlies are larger, with a distinctive hump on the shoulder. This is the most distinctive field mark from a distance. The face also differs from that of the black bear. The nose of grizzlies has a dished in appearance, while the black bear has a straight line from the forehead to the tip of the nose.

Range: Grizzlies are constantly being challenged by man, and this is rapidly reducing their North American distribution. They are found throughout the Canadian Rockies, but only in isolated pockets within the American Rockies. Glacier National Park in Montana is one particular US hot spot.

Diet: Since bears spend much of their life sleeping away winter in their dens, they have only one main focus when they are active—building up sufficient fat layers for next winters siesta. Unlike ground squirrels, which are true hibernators, bears merely go into a heavy sleep in the winter. This means that their metabolism, heart rate and respiration drop only slightly below what would be normal for such large animals. The end result is that they require almost as much food energy each day they spend in their den as if they were actively moving around.
Surprisingly, many bears continue to lose weight throughout the summer, even though they are up and actively feeding. In order to build up the fat layers required to sustain them through the winter, bears need foods with two characteristics. They must be highly nutritious and easily digested. During the annual cycle of life in the mountains, bears move with the availability of their primary foods. When grizzlies wake in the spring, they head to the avalanche slopes, make their way to the frozen food section and get themselves a TV Dinner. Over the course of the winter, the odd bighorn sheep, the odd mountain goat, and even the odd mountain climber falls victim to winter avalanches. These nicely preserved morsels give them the protein boost they need after their winter sleep. South-facing avalanche slopes are also one of the first areas to green-up in the spring, and so are attractive to bears.

Spring foods also include last years berries for instance bearberry, green vegetation, flowers, insects, animals, and garbage. Oh yes, and don’t forget to take down your bird feeder in the spring! Their diet is primarily composed of plants, and they actively hunt for the succulent new spring growth. Plants like the glacier lily and many members of the Pea Family sprout, the bear will quickly find them. The early stages of these plants are more nutritious, higher in protein, and more easily digested than the latter stages after they flower, and so bears will actively seek out younger groupings of plants.

Surprisingly, at high elevation, plants grow much faster and this provides a situation in which there is a greater amount of protein in the plants when compared to lower elevations. As a result, both black bears and grizzlies prefer to feet higher up the slopes.

In spring, when the high country is still snowbound, the bears are forced into the valleys which contain both roads and man. As a result, we tend to see more bears, particularly grizzly bears, during the spring months before they retreat uphill with the receding snowline. An early drive up the Icefields Parkway at this time is often rewarded with the sighting of at least one bear—perhaps even a grizzly.

As the season continues, the south-facing avalanche slopes and meadows begin to dry out, and their value as a feeding location diminishes. The bears look for moist areas where plants may still be in their early development stages. Moving from south to north facing slopes can delay green-up by a month or two, so the bears follow the green-up with an uncanny sense of where the most food will be located. During this time, there is a greater potential for conflict with hikers and other outdoors people. During this brief period, the berries have not ripened, and their early season foods have disappeared. On the other hand, these mid-season locations represent some of our most popular alpine meadows. Deep, north facing, avalanche slopes will have a very late melt and a subsequently late green-up. Of particular value, the Cow Parsnip (Heracleum lanatum) provides nutritious stems and occasionally leaf-stalks and flowers (rarely leaves). At lower elevations, black bears may feast on dandelions. Occasionally, roots of plants like the Hedysarum are critical.

Insects add to the diet. Where ever, how ever they can get them. Ants, beetles, bees, and anything else with six, eight or more legs. Since insects are prevalent in recent fire sites, caution is advised in these areas.

Mammals, like ground squirrels and taken when available. Bears eat more than 80% plant matter, and animals are an opportunistic event. As the calving season begins for ungulates, black and grizzly bears are quick to arrive on the scene. In some areas, grizzlies can take up to 50% of newborn elk and 42% of moose calves. The calves quickly mature though and can elude bears by a few days of age. For the rest of the season, only visibly sick or injured animals stimulate the predatory attention of bears. Animals that have died by other means, either predatory or otherwise, are also attractive. Carrion forms a critical part of the bear’s diet.

What about fish? Most people assume that grizzlies feed on salmon. Unfortunately for bears in the Rockies, there ain’t no salmon here. They must rely on other sources of food.

Finally, in mid-August, berries like buffaloberry (Shepherdia canadensis) begin to ripen. This is the peak feeding season. Finally we have plentiful, nutritional foods. Since buffaloberries have only a single seed, biologists can count the seeds in scats and get a great idea of the number of berries ingested (along with estimates of the number of daily defecations), biologists can estimate the number of berries and–and the numbers are immense. Bears will eat for up to 16 hour/day during this peak season and finally their weight begins to rise. They may feed on 50,000-200,000 buffaloberries each day. One study recorded an increase of 0.6 kg (1.4 lbs) per day during a 16 day period. In places like Banff National Park, where buffaloberry is plentiful, researchers have reported as many as 9 grizzlies within 3.1 sq. km (1.2 square miles). Huckleberries are also popular, along with sarsaparilla, Devil’s club, raspberry, strawberry, and crowberries. As berries, such as buffaloberry begin to fall from the branch with the approach of cold weather, bears begin to dig again for Hedysarum roots and related tubers until they head into their dens for the winter.

Reproduction: Grizzlies mate in the spring, and like members of the weasel family, experience delayed implantation, whereby the fertilized egg will float freely in the uterus for several months. Come autumn, if she is healthy, it will implant and begin to develop. They give birth to between 1 and 4 tiny cubs (usually 2) while in their winter den. In most populations, the cub will remain with the sow for one year, den with her the following winter, and be evicted in their second summer. In the central Canadian Rockies, research suggests that some cubs may remain with their mother for 3 or even 4 years. Since the sow will not mate until her cubs leave, this can greatly impact her frequency of reproduction.

Related Links:
The Eastern Slopes Grizzly Project is studying the grizzly in the Central Rockies Ecosystem, including Banff National Park and Alberta’s Kananaskis Country. The study began in 1994 to address the urgent need for scientific information about the cumulative effect of human development and activities on grizzly bears in this area.

Click here to learn how to differentiate black bears from grizzly bears

Click here for more information on bear safety