Bears are the largest carnivores on land, especially bears that weigh more than half a ton like polar bears and Kodiak brown bears, which are rare for animals to provoke. Although in the impression of most people, bears are animals that need to hibernate, in fact, not all bears need to hibernate. For example, spectacled bears do not have the habit of hibernating. So why do those hibernating bears hibernate? Do hibernating bears have the ability to protect themselves when they encounter tigers? Let’s discuss these two issues together.
Why do bears hibernate?
Under normal circumstances, hibernation is common in ectothermic animals living in temperate and frigid regions. Because they cannot regulate their body temperature, in order to avoid the severe cold, they will find a place with a relatively constant and high temperature to sleep deeply. This short sleep time One or two months, or half a year. That is to say, hibernation is a way that ectothermic animals are forced to choose to avoid the severe cold.
However, bears are a kind of warm-blooded mammals. They are huge in size and covered with thick hair. They should not be afraid of severe cold. So, why do they choose to hibernate? The main reason is the food.
In the entire bear family, except for polar bears whose food is mainly pure meat, other brown bears, black bears, spectacled bears, and giant pandas are omnivores, and plant food accounts for a large proportion. The ratio exceeds 60%, the proportion of plant-based food for black bears even exceeds 80%, and the proportion of plant-based food for giant pandas even reaches 99%.
The high proportion of plant food means that the energy supply of these animals mainly depends on various plants (including fruits, roots, stems, etc.), but in temperate and frigid regions, once winter comes, everything withers, and plant food is almost disappeared completely. At this point, the bears enter a period of food scarcity. Therefore, in order to survive the period of food scarcity, most bears choose to hibernate. And bears that live in the tropics or have sufficient food in all seasons, such as spectacled bears and giant pandas, do not need to hibernate.
In fact, for warm-blooded animals, maintaining a relatively stable body temperature itself requires a lot of energy. The same is true for bears. During periods of food scarcity and low temperature, if they do not hibernate, they need more energy to maintain their body temperature, so , they have to hibernate, which is what we often call forced hibernation. Before hibernation, the body temperature of bears will drop by about 4°C to reduce energy consumption, so at the same time, their heart rate will be reduced by 75%, and the slower metabolic rate will also reduce their energy consumption to the extreme. At this time, the hibernating bear only needs to slowly convert the fat stored before hibernation into the energy that maintains the minimum vital signs to survive the cold winter for several months.
Will hibernating bears be eaten by tigers?
Hibernating bears are eaten by tigers, which can only occur in temperate and subarctic regions of Asia, because tigers are only distributed in parts of Asia. From a distribution point of view, the tiger that overlaps with bears the most is the Siberian tiger. In the habitat of the Amur tiger, it can encounter the Asiatic black bear (Northeast Asian species) and the Ussuri brown bear. The most important thing is that these two kinds of bears have the habit of hibernating in winter, while the Siberian tiger at this time does not hibernate, but constantly searches for prey in the snow.
So, is it possible for the Siberian tiger to drag out the hibernating bear and eat it? The answer is yes. Just last year, an incident of Siberian tigers eating black bears occurred in Taipinggou Nature Reserve in Heilongjiang Province. At that time, the staff of the reserve found a series of footprints of Siberian tigers when they were doing wildlife surveys. Following the footprints, the staff found a black bear that had been eaten by most of them, and not far from the black bear, there was a black bear. There are obvious signs of fighting around the cave. Since it happened to be winter, the black bear hibernation season, experts determined that this was a case of Siberian tigers actively hunting and killing hibernating black bears, and this was the first time in my country that wild Siberian tigers were found eating hibernating black bears. (The picture below shows the hibernation cave discovered by the staff not far from the black bear carcass)
Although bears in hibernation are indeed hunted by tigers, during hibernation, only black bears are killed, and no adult brown bears are killed. What is the reason for this result? There are two main factors:
01 Selection of hibernation places
Although both black bears and brown bears hibernate, they have certain differences in the choice of hibernation places. Brown bears usually choose to dig holes or tree holes (rock caves) on hillsides with more dead branches and better concealment. Although most black bears choose hibernation places similar to brown bears, according to the analysis of the hibernation places of black bears that were eaten before hibernation, these black bears usually choose less concealed tree holes and burrows, and most of these burrows are It is shallow and the opening is larger.
Therefore, brown bears can respond to tigers in advance by the sound of animals stepping on dead branches, while black bears have poor ability to predict the patronage of tigers.
02 Difficulty of hunting
Under normal circumstances, hibernating animals almost enter a state of “suspended death”, such as hedgehogs, snakes, etc. Even if these animals are found during hibernation, they will not notice. However, bears are different. Bears have a certain alertness in hibernation. They may wake up at any time in a semi-sleep state, and even come out for a stroll at noon when the temperature is relatively high. This hibernation habit is conducive to their timely detection of danger. And whether it is a brown bear or a black bear, when hibernating, they will enter the burrow backwards, so that the head can face the danger in time. Therefore, it is difficult for Amur tigers to hunt and kill any kind of hibernating bears. However, in terms of body size, the average weight of adult male black bears is about 130 kg, the average weight of females is about 90 kg, and the average weight of adult male Ussuri brown bears is about 260 kg. Even smaller females have an average weight of about 90 kg. 160 kg body weight. For Amur tigers with an average weight of about 190 kilograms, hunting black bears smaller than themselves is obviously the least risky and has the highest success rate.
Summarize
The bear is a constant temperature mammal. In the cold winter, it consumes a lot of energy to maintain its body temperature. In addition, the bear’s diet is an omnivorous and partial herbivorous animal. In winter, its food decreases sharply, so , it must hibernate in order to escape the cold and reduce its need for food.
Since the habitat of some black and brown bears overlaps with that of the largest cat, the Amur tiger, which is a non-hibernating predator, the tiger will indeed kill the hibernating bear during the bear’s hibernation period. However, it is limited to smaller black bears, and because bears are still vigilant when hibernating, tigers must fight if they want to eat bears.