Grizzly

Grizzly

THE SPECIES: Ursus arctos

Respected by all, the grizzly bear is a symbol of wilderness, of something out there that is bigger and stronger than us. If you've been lucky enough to see a grizzly in its environment, you know for certain that this is one of our most powerful northern land mammals.

The grizzly is a circumpolar animal. Its doughnut-shaped range extends from the Arctic coast down into the central parts of Europe, Asia and North America. Within this range, some areas provide more food and are subject to shorter winters than others. Different conditions like these produce different types of grizzlies: bears that vary in size, body proportion, colour, and lifestyle.

DISTRIBUTION

Grizzly bears inhabit the entire Yukon, from the B.C. border to Herschel Island off the Arctic coast. Since the Yukon's northern interior environment is less productive than southern or coastal environments, our bears are spread fairly thin over the landscape. The territorial population is estimated at 6,000 - 7,000 animals.

CHARACTERISTICS

The colour of Yukon grizzlies ranges from near black to silver-blonde. The typical bear shows darker colours on its legs and belly and lighter colours on its back. It is the lighter tips of the long guard hairs that give this bear its "grizzled" appearance.

Northern interior grizzlies are smaller than the southern grizzlies that benefit from longer foraging seasons. They are also smaller than Alaskan coastal grizzlies that thrive on rich salmon streams. Adult Yukon males generally weigh 225 to 275 kilograms -- about half the weight of the largest bears from the Kodiak Islands of Alaska. The heaviest grizzly studied in the Yukon tipped the scales at 430 kilograms (940 lb.), and likely benefited from a garbage enhanced diet.

The denning period varies among different populations of grizzlies, depending on the regional climate. Yukon bears spend six to seven months -- October through April -- in their winter den. Yellowstone grizzlies spend only five months in the den.

An important characteristic of northern grizzlies is their low rate of reproduction. Yukon bears begin to breed later in life than other bears and reproduce less often. For example, female grizzlies in the Kluane area breed for the first time at seven years of age, and every three to four years afterwards.

UNPREDICTABLE OR ADAPTABLE?

You'll often hear the comment that grizzlies are unpredictable, but this is somewhat misleading. A more accurate statement is that grizzlies are highly adaptable. The life of this omnivore centers around an intensive search for the most nutrient-rich foods it can find. Individual bears learn successful methods of achieving this goal; methods that vary greatly between regions and, to some degree, between individuals. Generally, in a given region, all bears will focus on the same set of foods at the same time. But some individuals are able to exploit additional localized food sources. For example, in mid-May, virtually all Yukon grizzlies are eating roots and overwintered berries. A little later in the season, bears that have learned to capture moose and caribou calves focus on this food source while others concentrate on newly emerged grasses, sedges, and horsetails.

Every adult bear has learned a unique set of feeding sites based on its mother's training and its own ramblings. Because of its much larger home range, a male is able to include unusual food resources like spawning salmon in its diet.

Finally, bears, like people, vary in their aggressiveness. At the top end of the aggression scale are females with young cubs. Grizzlies generally avoid conflict with humans however, and, if we manage our own food and garbage carefully, co-existence between our two species is not difficult.

A YEAR IN THE LIFE

Winter

In its warm mountainside den, a Yukon grizzly escapes the blowing snow and -40 C temperatures of the northern winter. Its heart rate and breathing rate are lowered but its body temperature remains near normal. As a result, it can wake up quickly. A thick layer of fat provides for the bear's low energy needs during this period when it doesn't eat or drink. The marvelous recycling of fluids and wastes that takes place inside a denning bear is the subject of intensive study by biochemists and physicians.

In February, while in the den, a pregnant female will give birth to one, two, or occasionally three cubs. Less than half a kilogram in weight, the young begin to nurse immediately and will not leave the den for the first time until three months have passed.

Spring

Spring is a season of rebirth for all life in the Yukon. Male grizzlies emerge from their winter dens in late March or early April. At treeline, the snow generally lies heavy at this time of year, but south facing slopes are usually bare. Here the bears might turn over the soil to get at the starchy roots of Eskimo potato.

In the subalpine zone, grizzlies feed on overwintered cranberries and bearberries while searching for marmots and ground squirrels. Except for females with newborn cubs, bears roam widely at this time of year, looking for winter-killed carrion, weakened animals, and newborn moose or caribou calves. At river level, the roots of Eskimo potato and horsetails are a primary food source in spring.

Most Yukon grizzlies breed during the month of June. A breeding pair will stay together for a week or two at most.

Another social unit is formed by a sow and her cubs. Females with newborn cubs remain in their dens about a month longer than other bears. This is done to give the cubs a better chance of survival. Even then, about 1/3 of all cubs die, usually as entire litters, before the end of the breeding season. The patterns of these losses are not well understood. Other bears, particularly transient males may be an important factor as they are known to kill the young.

The cubs stay with their mother for two or three years, denning with her each winter. The female will not breed again until the family has broken up. Siblings may also form a social unit after separating from their mother, and often den together the first winter on their own.

Summer

In mid-summer, grizzlies will often be found in alpine settings, feeding on new growths of grasses and horsetails. Many bears are attracted to the river flats in mid-July when soapberries ripen. These red berries are a staple food source until other berries ripen in August.

To escape the mid-day heat of summer, grizzlies rest in shallow scrapes in the cool earth. These daybeds are roughly one meter in diameter and 25 centimeters deep. They are usually found near feeding areas; in shady spots near streams or meadows, and on cool snow patches and riverside sandbars.

Fall

When berries ripen in August, a change takes place in the grizzly lifestyle. Propelled by a voracious appetite and an approaching winter, the bears gorge themselves on large quantities of berries. This is the only time of the year when bears actually put on weight: up to one kilogram per day. In other seasons they are either stable or losing weight.

The fall weight gain of grizzlies varies by region based on the foods available in each area. The primary food source at this time of year in the Kluane region is soapberries. In the central Yukon it is blueberries; in the northern Yukon, in some years, it is ground squirrels.

Yukon bears do not have access to the heavy salmon runs of coastal rivers, but many streams in the Yukon river drainage host moderate runs of salmon in late summer and early fall. Some grizzlies in the Tatshenshini/Klukshu area put on fat at this time of year by feeding on those streams' salmon runs. Bears near the Fishing Branch River in the northern Yukon, take advantage of this stream's unusual late season chum salmon runs.

Fallen berries and the first frosts of the season signal the approach of winter. In October, bears begin to move towards the high country as the denning period approaches. Grizzlies usually den on south facing slopes near treeline. To create a denning cavity, a bear might move as much as a ton of earth out of the hillside. The dens are about one meter high and one and a half meters in diameter. They are connected by a one- to two-meter tunnel down and out to the "porch" made from the pile of removed earth. A clean mattress of grasses, moss, and twigs lines the den. What a sensible way to spend a Yukon winter!

GRIZZLIES AND PEOPLE

Yukon First Nations shared the landscape with grizzly bears for thousands of years. A person who met a grizzly on the trail or in a berry patch would speak quietly to the bear, explaining that he was out hunting moose (or she was out gathering berries) to feed the family and meant no harm to the bear. Grizzlies were rarely hunted in those times. Before the arrival of firearms only the bravest men hunted bears. If a den was discovered in the winter, a group of hunters might return in the spring to try and kill the bear in close combat, with spears and clubs. Slain grizzlies were treated with special honour and respect.

Most of the early prospectors and trappers considered the grizzly to be a dangerous, almost evil animal. In reaction to the occasional maulings and damage to cabins and food caches often shot bears on sight.

Nowadays, Yukoners have come to appreciate the value of this rare and exciting animal and accept responsibility for avoiding conflicts. We are proud to share our living space with one of the world's largest remaining grizzly populations.

VIEWING OPPORTUNITIES

Highway travellers might catch sight of a grizzly bear on just about any road in the Yukon, but the odds of such a sighting are slim. In normal circumstances, bears avoid humans and their sign. The Dempster Highway probably offers the best chance to observe a grizzly from the roadway.

River travellers are much more likely to observe grizzlies, particularly in early spring and late fall. Salmon streams like the Tatshenshini and Big Salmon Rivers can provide good grizzly viewing at certain times, but there are two risks involved. First there's the need to keep a good distance between yourself and the bear (easier said than done on a small river). Then there's the whitewater to deal with, particularly on the Tatshenshini River (rafts and kayaks only).

Hiking is the best way to get into grizzly viewing territory above treeline. In alpine habitat, vegetation is sparse, long distance views are common, and grizzlies are present throughout the seasons. Open vistas allow hiker to observe grizzlies at safe distances. Kluane National Park is an ideal area for safe bear viewing.

IDENTIFICATION

Most of us can easily tell the difference between a bear and a moose, but are less sure about the difference between a black bear and grizzly in the field.

When you encounter a bear take note of the following features:

Hump -- grizzly bears have a pronounced hump of muscle over their shoulders, black bears do not.

Face -- the side profile of a grizzly bear will reveal a concave or dished area between the nose and eyes. The side profile of a black bear will reveal a straight line between nose and eyes, and a light colored nose mask.

Claws -- grizzlies have longer claws than black bears. This is most noticeable on the front feet where grizzly claws can reach 10 cm in length.

Chest Patch -- grizzlies do not have a white chest patch; many black bears do.

DID YOU KNOW

The grizzly is the largest land carnivore in North America. It fears only one other species: humans.

One-quarter of Canada's grizzly bears live in the Yukon.

Yukon grizzly bears have one of the lowest reproduction rates of all North American mammals.

In an autumn feeding frenzy, a grizzly can eat 200,000 berries in a single day.

Grizzlies stand up on their hind feet, not to attack, but to get a better view while they test the air and try to identify you.

In captivity, grizzlies have been successfully bred with polar bears. This is one reason why biologists suspect that polar bears evolved from grizzlies.