Polar bears and modern brown bears are descendants of ancient brown bears, but the difference between them is only a few hundred thousand years. However, there are some differences in their morphological structure. Polar bears have a small head, a long neck, a long body, inconspicuous shoulders and a big ass. Brown bears have big heads, short necks, short bodies and prominent shoulders. Therefore, polar bears have an absolute advantage in body length, while subspecies brown bears have considerable strength with polar bears in skull size and shoulder height.
In view of the differences in morphological structure between the two bears, we can only compare their size and weight scientifically. The weight data circulating on the Internet can be said to be varied, but these are often not reliable sources. Therefore, this paper only compares the scientific research data, that is, the weight data measured by scientists and officially published in academic literature. At the end of the paper, the data sources are listed, and the reference materials can be consulted in databases such as HowNet.
It is indisputable that polar bears are larger than average.
The public is more interested in the final weight of these bears, and in scientific statistics, the average weight is a relatively stable indicator, and the maximum value of the sample depends largely on the sample size.
There are more than 20 subspecies in the world and only 5 subspecies in Alaska, USA. Unlike animals, which usually travel north and south, and mainland islands are small, Alaska brown bears are just the opposite, and the brown bears in southern coastal islands and peninsulas are the largest. The Kodiak brown bear on Kodiak Island has an average of 365,438+02kg for males over 6 years old and 202kg for females, while the alaska peninsula giant subspecies (Peninsula Giant Brown Bear) has an average of 365,438+098kg for males over 5 years old and 65,438+098kg for females in spring.
The only subspecies of brown bear that can be compared with polar bears are Kodiak brown bear and Peninsula brown bear. Brown bears in Alaska mainland belong to Alaska subspecies. Male bears generally weigh only about 200 kg, and female bears 1 10 kg. There are Sitka Brown Bear and Das Brown Bear in the "Pot Handle" area in southeastern Alaska, with an average male of 270kg and female of 170kg. None of these can be compared with polar bears.
So to correct a statement, the largest subspecies of brown bear are Kodiak brown bear and Peninsula brown bear, not "Alaska brown bear".
Although polar bears are a whole in the world, there are still some size differences among sub-populations in different regions. Taking adults over 5 years old as an example, the average weight of adult male polar bears in South Hudson Bay is 489 kg, that in Chukchi Sea is 46 1 kg, and that in South Beaufort Sea is 368 kg. The largest is Fox Bay, with an average of 565,438+00 kilograms for adult male bears.
It can be seen that compared with the average weight, brown bears are hard to compare with polar bears, and it is indisputable that polar bears are the largest bears.
Tian Ji Horse Racing, Can Brown Bear Beat Polar Bear?
Comparing the largest subspecies of brown bears with polar bears is already a celestial race, but we find that brown bears are still inferior. It seems that brown bears have to think of other ways to win the title of the biggest bear.
1. Body mature weight
Male brown bears and polar bears are sexually mature at the age of 5, but then their bodies will continue to grow for a while. The subspecies brown bear didn't reach physiological maturity until he was in his teens. /kloc-Peninsular brown bear over 0/0 years old, with an average of 389 kg in male and 207 kg in spring.
On the other hand, polar bears grow faster than peninsular brown bears, depending on different regions. The male bear in Hudson Bay is physically mature at the age of 5. Individuals in Beaufort Sea reach 97% of their mature weight at the age of 7, while the largest polar bear in Persian Gulf grows longer.
Polar bear experts measured a large number of individuals and calculated by formula fitting, giving the mature weight of polar bears from all over North America and Norway (below). We just compared it with the peninsula brown bear. The polar bear in Europe is usually considered as the smallest in the world. The male bear in Svalbard, Norway weighs only 389 kilograms, which is as big as the peninsula brown bear. Polar bears in North America and Siberia are still significantly larger than brown bears, with 557 kilograms in Chukchi Sea and an astonishing 579 kilograms in Fox Bay!
It seems that the mature weight of brown bears is a little big, but it is still dwarfed by polar bears.
2. Autumn weight
There is a unified standard for measuring the weight of bears in scientific research, generally weighing in spring. The weights of polar bears and brown bears mentioned above are all in spring except Kodiak brown bears in summer.
The seasonal variation of polar bear weight is relatively small. In populations farther south, such as Hudson Bay, male bears are the lightest when they thaw in autumn. Farther north, such as Canada's high-latitude Arctic, the population in spring is relatively small. Polar bears living between Beaufort Sea and Chukchi Sea may have no obvious seasonal fluctuation.
The weight of brown bear changes obviously in four seasons, with the heaviest in late autumn before hibernation, lighter in spring and lightest in summer. For men, autumn is about 24% heavier than spring.
In this way, the male peninsula brown bear and Kodiak brown bear, whose average physical maturity is close to 400 kg in spring, may weigh 490 kg in autumn. This weight has surpassed that of the northern polar bear in Beaufort Sea, reaching the level of South Hudson Bay (486) and davis strait (48 1), but it still lags far behind Chukchi Sea (557) and Fox Bay (579).
3. Weight of the female bear
Polar bears are more hermaphroditic than brown bears, so the gap between females and males is smaller. The average weight of the mother peninsula brown bear and Kodiak brown bear is above 200 kg, which is obviously higher than that of Norwegian female polar bear 185 kg, and almost as big as Beaufort Sea. But the female polar bears in Fox Bay, davis strait and Chukchi Sea are all 250kg, much larger than the female brown bear.
In scientific research, the polar bear is also very heavy, because it is weighed in spring. At this time, the female polar bear who was pregnant and gave birth last year has just finished hibernating and her physical condition is relatively poor. Her weight is at the lowest point in a year, and the male bear doesn't hibernate. Brown bears hibernate regardless of sex.
4. Maximum weight
Among the individuals weighed in scientific research, the largest polar bear in Norway is 5 10kg, the largest in Beaufort Sea is 6 10kg, the largest in Chukchi Sea is 6 14kg, the largest in Hudson Bay is 654 kg, the largest in East Greenland is 680 kg, and the largest in Fox Bay is 8/kloc. The heaviest Kodiak brown bear 6 1 1 kg (autumn).
In the hunting records recognized by experts, the largest Kodiak brown bear weighs 75 1 kg, while the largest polar bear weighs 1002 kg.
It can be seen that the largest individual is also a polar bear.
Polar bears are not terrestrial animals.
To sum up, it is undisputed that polar bears are the largest bears, but they may not be considered as terrestrial animals, although their morphological structure is more in line with terrestrial animals. The definition of terrestrial animals, on the one hand, looks at the base of their lives, that is, they are not standing on land; On the other hand, it depends on its nutritional source, that is, whether the food comes from the terrestrial ecosystem.
These two aspects are not consistent with polar bears. Polar bears live on sea ice, and their foraging, courtship and mating activities are all carried out on sea ice. Sea ice still belongs to the Arctic Ocean, not land. Its food source seals, walruses and beluga whales are all marine animals, not land animals. When polar bears land, either the sea ice completely melts and temporarily lands for refuge, or the pregnant female bears land for hibernation and give birth. Polar bears sometimes find some plants and garbage on land to satisfy their hunger, but this is of little value to their nutrition and reproduction.
Giving birth to cubs is the only important life activity that polar bears usually complete on land, but it is not necessary. Female polar bears in Beaufort Sea nest and give birth on sea ice, completely out of land restrictions. So strictly speaking, polar bears are not terrestrial animals. The Food and Agriculture Organization of the United Nations (FAO) clearly listed polar bears as marine animals when compiling the list of marine mammals in the world, and the Red List of the World Conservation Union (IUCN) also called polar bears as marine animals.
Summarize the main points of this paper: the biggest brown bear is not Alaska brown bear, but Kodiak brown bear and Peninsula giant brown bear; However, even these two subspecies are not as big as polar bears. The brown bear is indeed the largest terrestrial carnivore, but this is not because it overtook the polar bear, but because it drove the polar bear out of the land.
Is brown bear a carnivore?
It is often said that brown bears are omnivores rather than carnivores. There are three points to emphasize here:
Taxonomically, bears are carnivores, so of course they are "carnivores".
Brown bears must eat meat, especially in spring. The plant-based diet can't fully meet the needs of bears, which is essentially different from wild boar and baboon. Wild boar and baboon are real omnivores and occasionally eat meat.
Among the subspecies of brown bear, Tibetan horse bear is a pure carnivore. Brown bears in many areas prey on ungulates to varying degrees, and brown bears by the sea also catch a lot of salmon.
If the carnivorous status of brown bears is questioned because they eat more berries and prey less ungulates, there are many kinds of insects and plants as the staple food of canines and civets, while wolverines and brown hyenas rarely hunt by themselves. The only "pure carnivores" who really meet the requirements are cats, gray wolves and a few large canids, hyenas and some weasels. If we only say "pure carnivores", then big cats such as tigers and lions are the biggest.
Therefore, brown bears are undoubtedly carnivores, but their roles in the ecosystem are mostly scavengers, not carnivores like polar bears, tigers and wolves.
Being big does not mean being strong, and being strong does not mean living better. I hope you don't worry about which of these animals is bigger. Zoology will introduce the evolutionary relationship, competitive relationship and their living conditions of polar bears and brown bears one by one in the future, so please pay attention.
refer to
Charles Schwartz, Sterling Miller and Mark Harrods (2003). Grizzly bear. Wild Mammals in North America: Biology, Management and Protection (2nd Edition)
Steven c amstrup (2003). Polar bear. Wild Mammals in North America: Biology, Management and Protection (2nd Edition)
Leland p Glenn (1980). Morphological characteristics of brown bear in central alaska peninsula.
A. Escherichia coli (199 1). Population dynamics and ecology of polar bears in western Hudson Bay
A.e. drocher and é. Wiig (2002). Growth of body length and weight of polar bears in Svalbard after birth
Eric v raiguel, Steven c amstrup and Ian stirling (2006). Population status of polar bears in the South Beaufort Sea
Karyn Rode and Eric V. Regehr (20 10). Polar Bear Research in Chukchi and Bering Sea: A Summary of 20 10 Field Work
Karyn Rode et al. (20 13). Changes in the response of top Arctic predators experiencing habitat loss: feeding and reproductive ecology of two polar bear populations