Brown bears appeared in Eurasia about 50,000 years ago. Some of them also moved to North America, where they spread and live for about 13,000 years. In the 19th century, scientists classified 86 separate species of grizzly bears that live on the North American continent. However, by 1928 the scientific community narrowed the number down to seven, and by 1953 only one species had been identified.
In 1963, it became clear that the grizzly was not a separate species, but a subspecies of the brown bear, and this was confirmed by modern genetic testing. According to external differences and habitat, several of its subspecies were distinguished, however, the classification was revised along genetic lines, and today there are two morphological forms: the continental and coastal grizzly bear. In scientific sources, it is customary to call it the North American brown bear.
External Features
As with other subspecies of the brown bear, the brown color of the grizzly's coat can vary from light beige to almostblack. In the latter, the coat color is distinguished by a darker shade on the legs and lighter on the back. In the representatives of the Rocky Mountains, the tips of the outer coat are white, which gives the animal a grayish color.
External signs of a grizzly bear and a brown bear have a number of characteristic features. As the animal matures, a well-defined hump develops at the withers, which is a good way to distinguish a grizzly from a black bear that lives in the same area. Small, rounded ears and a croup below the shoulder line is an anatomical structure that is also distinctive for a brown bear and not inherent in a black one. These two species are also distinguished by the length of the front claws, which in the black representative is 2.5-5 cm, and in the grizzly it is about 5-10 cm, which corresponds to the size of the claws of other brown bear subspecies.
Size and weight
The main difference between the grizzly bear and the Eurasian brown bear is size and weight. Coastal representatives of the species are larger than those that live in the depths of the continent, and just like all of the bear family, females are smaller than males. Most adult bears reach 130-180 kg, and males usually weigh 180-360 kg, newborn cubs do not exceed 500 grams. The average weight of coastal grizzlies is 408 kg for males and 227 kg for females. The corresponding weights for continental bears are 272 and 227 kilograms.
Average subspecies sizes:
- length -198cm;
- height at withers -102 cm;
- hind legs length - 28 cm.
However, specimens have been recorded that are significantly larger than normal size and weight. An example of the largest grizzly bear is known - a coastal male weighing 680 kg and 1.5 meters high at the withers. Standing on its hind legs, this bear reached almost three meters in height. Grizzlies are sometimes oversized and overweight, but they are erroneous because they correspond to the parameters of Kodiaks, another larger subspecies of the brown bear.
Area and abundance
In North America, grizzlies once lived from Alaska to Mexico. Now, including Canada and the United States, their range has halved, and the number is 55,000 wild bears. The places where the grizzly bear lives are limited to Alaska, the vast territory of western Canada, the northwestern United States, including Idaho, Washington, Montana and Wyoming, to the south of Yellowstone and the Great National Parks.
Most of the population lives in Alaska. In Canada, the predominant number of bears is registered: about 25,000 individuals inhabit British Columbia, Alberta, Yukon, the northwestern territories of Nunavut and northern Manitoba. The University of Alberta estimated that there were 16,014 grizzly bears in British Columbia in 2008 and 15,075 in 2012. Modern population counts are based on a DNA sample base, a recapture method, and an advanced multiple regression model.
There are about 1,500 grizzlies left in the US. Fromabout 800 of them live in Montana, 600 bears live in the Yellowstone-Teton region of Wyoming, 70-100 are observed in northern and eastern Idaho.
Population decline
The original range of the grizzly bear in the United States included the Great Plains and most of the southwestern states, but the population was exterminated in most of these areas. Prior to California's accession to the United States, its national flag featured the California Grizzly, which was the symbol of the Republic. The last bear in all of California was killed in the foothills of the Sierra in August 1922. In Colorado, the last representative was seen in 1979. And there are now fewer than 20 grizzly bears in the vast Cascades of Washington State.
The decline in the population has been significantly affected by hunting and the development of human activities occupying the former habitats of grizzlies. Other factors:
- competition with other, more adaptable predators;
- attack on grizzly cubs;
- reproductive, biological and behavioral properties of brown bears.
Lifestyle and reproduction
Except for females with cubs, all brown bears are solitary animals. An exceptional feature of large grizzly bears in coastal areas of North America is to gather in groups near streams, lakes, and rivers during salmon spawning. Each adult male grizzly takes care of personal possessions up to 4000 km22. Sucha large territory and low population significantly complicate the search for the scent of a female. The grizzly bear hibernates 5-7 months of the year.
The grizzly bear has one of the lowest reproductive rates of any land mammal in North America. Animals reach sexual maturity only at the age of at least five years. After the summer mating season, the female can delay the implantation of the embryo until hibernation, which explains the large difference in gestational age - from 180 to 250 days. If the bear does not receive proper nutrition, the necessary calories and substances, then the embryo will miscarry.
Litter size ranges from one to four cubs, but more often twins or triplets are born, which the female produces during hibernation. The mother bear takes care of the cubs for two years, during which she does not mate. Often cubs do not live up to this age, becoming victims of predators. During the time spent with the mother, the cubs gain weight up to 45 kg. When two-year-old bears leave their mother, the female bear cannot produce another litter for three or more years, depending on environmental conditions.
Lifespan
The grizzly bear is a long-lived animal. Males, on average, live up to 22 years, and the age of she-bears often exceeds 26 years. Females live longer than males due to safer behavior and the fact that they do not participate in the seasonal mating battles of males. The oldest wild continental grizzly has been recorded in Alaska, helived 34 years. The oldest coastal bear lived to be 39 years old. At least 50% of grizzlies living in captivity live to be 44 years old. But most bears die in their first years of life from predators or hunting.
Attacks on people
Like the polar bear, grizzlies are considered more aggressive than other species. However, threatening behavior is more often due to the protection of offspring. She-bears guarding cubs are the most prone to attack. They are responsible for 70% of bear attacks on humans. At the same time, the heavy-weight grizzly bear is rather slow and, unlike smaller black bears, does not climb trees well, and prefers to react to danger by standing still and driving away attackers with a wave of its paws, a growl and menacing nods of its head.
In an article by Cardall and Peter Rosen, "Attack by a Grizzly Bear," published in the journal Emergency Medicine, it was noted that 162 injuries inflicted by bears, including fatal ones, were recorded in the United States from 1900 to 1985. This amounts to approximately two cases per year. For comparison: in the US and Canada, up to 15 people die each year from dog attacks, and lightning strikes kill close to 90 people a year.
