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15 Best Facts About The Brown Bears

Brown bears, members of the genus Ursus, are large bears that can be found in both Eurasia and North America. Brown bears found in North America are referred to as grizzly bears, while the Kodiak bear is the term given to the subspecies found in the Kodiak Islands of Alaska. It is one of the largest terrestrial carnivores alive today, only slightly smaller than the far less variable and somewhat larger-than-average polar bear (Ursus maritimus) in terms of size.

Large areas of Europe, Asia, North America, and Eurasia may harbour brown bears, including the Balkans, the Picos de Europa and the Carpathian region (especially Romania), Iran, Anatolia, and the Caucasus. The brown bear is cherished as a national emblem all across Europe.

1. Brown bears are thought to have evolved from Ursus etruscans in Asia

Kamchatka Brown Bear near Dvuhyurtochnoe on 2015-07-23.jpg, , via Wikimedia Commons

The Asian brown bear (Ursus etruscus) may have bred with the brown bear. Kurten 1976 says the brown bear “clearly derived from the Asian population of Ursus savini about 800,000 years ago; spread into Europe, to the New World.” Molecular dating puts the brown bear’s genetic divergence from the cave bear species complex around 1.2-2 million years ago, although it’s unknown if U. savini became a paraspecies or went extinct.

Chinese fossils from this species date back half a million years. Brown bears arrived in Europe 250,000 years ago and North Africa shortly after. British Isles Pleistocene brown bear fossils suggest that these bears outcompeted cave bears (Ursus spelaeus).

The animal first appeared in Alaska 100,000 years ago but began migrating south 13,000 years ago. Before dying, the massive short-faced bear (Arctodus simus) blocked brown bears from migrating south.

2. The brown bear is the most variable in size of modern bears

The brown bear is the most variable in size of modern bears. The typical size depends upon which population it is from, and most accepted subtypes vary widely in size. This is in part due to sexual dimorphism, as male brown bears average at least 30% larger in most subtypes.

Individual bears also vary in size seasonally, weighing the least in spring due to lack of foraging during hibernation, and the most in late fall, after a period of hyperphagia to put on additional weight to prepare for hibernation. Therefore, a bear may need to be weighed in both spring and fall to get an idea of its mean annual weight.

7. Brown bears are listed as a Least concern species by the IUCN

While the brown bear’s range has shrunk and it has faced local extinctions, it remains listed as a Least concern species by the IUCN, with a total population of approximately 200,000. As of 2012, this and the American black bear are the only bear species not classified as threatened by the IUCN.

However, the California grizzly bear, Ungava brown bear, Atlas bear and Mexican grizzly bear, as well as brown bear populations in the Pacific Northwest, were hunted to extinction in the 19th and early 20th centuries and many of the southern Asian subspecies are highly endangered. The Syrian brown bear is very rare and it has been extirpated from more than half of its historic range.

One of the smallest-bodied subspecies, the Himalayan brown bear, is critically endangered, occupying only 2% of its former range and threatened by uncontrolled poaching for its body parts. The Marsican brown bear in central Italy is believed to have a population of just 50–60 bears.

8. The brown bear is often described as nocturnal

People often say that the brown bear is a night animal. But it seems to be busiest in the morning and early evening most of the time. Studies have shown that bears can be active almost any time of day or night. Bears who live in places where people are more common are more likely to be active only at night.

Also, young bears and bears that just got their independence are more likely to be busy during the day, while many adult bears in low-disturbance areas are mostly nocturnal. In the summer and fall, a brown bear can gain up to 180 kg of fat, doubling its weight from the spring. This fat helps it get through the winter, when it is very lazy.

Even though they don’t fully hibernate and are easy to wake up, both sexes like to den up in a safe place during the winter. Hibernation dens can be any place that protects them from the weather and can fit their bodies, like a cave, a crack, a hole in a tree, or a hollow log.

9. Brown bears communicate using facial expressions and vocalizations

Brown bears communicate by facial expressions and vocalisations. Face expressions have caused several behaviours. Brown bears have a “relaxed face” with ears pointed to the sides and a closed or slack mouth. During social play, they have a “relaxed open-mouth face” with a curled upper lip, drooping lower lip, and alert shifting ears.

An aggressive “jaw-gape face” has exposed lower canines and drooping lips. During hostility, the “biting face” resembles the calm open-mouth face but has flattened ears and wide eyes to show the sclera. Aggressive bears can switch between biting and jaw-gaping faces.

Brown bears also vocalise. When disturbed, they huff at two per second. Bears woof in alarm. Grrrls to rumbles are growls. Brown bears vocalise their emotions, threat levels, and social interactions.

10. Brown bears usually occur over vast home ranges

Brown bears typically have large home ranges, but they are not very possessive of their territory. Unless there is a dispute over a fertile female or a food source, multiple adult bears frequently roam freely in the same area. Every year, males always cover a larger area than females. Adult males can appear to have a “personal zone” where other bears are not permitted if they are sighted, despite the fact that they do not exhibit regular territorial behaviour.

While females benefit from smaller territory in part because it reduces the possibility of confrontations with male bears who might endanger their cubs, males always move farther than females due to increased access to females and food supplies.

11. The mating season of brown bears is from mid-May to early July

Mid-May to early July is the time for mating, with the timing moving later the further north the bears are found. Brown bears are serial monogamous, which means they spend anywhere between a few days to a few weeks with the same spouse. Adult male and female brown bears do not exhibit sexual interest in one another outside of this brief window.

Males first mate around a year later on average, when they are big and powerful enough to successfully compete with other males for mating rights. Females reach sexual maturity between the ages of four and eight, with an average age at sexual maturity of 5.2 to 5.5 years. Males will attempt to mate with as many females as they can; typically, a successful mating takes place between one and three weeks later between two females.

The adult female brown bear exhibits a comparable level of promiscuity, breeding with two guys in one day and mating with up to four, if not eight, males while in heat. With a whole range of 2.4 to 5.7 years, females enter oestrus on average every three to four years.

12. The brown bear is one of the most omnivorous animals in the world

One of the omnivorous animals in the world, brown bears have been observed to eat the widest variety of foods of any bear. This species is constantly interested in the possibility of consuming almost any creature or object it comes across. Food that is both plentiful and simple to obtain or catch is preferred. To accommodate their food preferences, their jaw shape has changed. Due to opportunity, their food varies greatly in each of their different habitats.

Despite their reputation, brown bears are generally not very carnivorous because up to 90% of their nutritional energy comes from plant stuff. They frequently consume a wide range of plant materials, including berries, grasses, flowers, acorns, pine cones, and fungi like mushrooms. Brown bears are the only bears with the special ability to dig for hard meals like roots, bulbs, and shoots.

To get to the roots, they dig out the soil with their long, powerful claws and then bite through them with their powerful teeth. Carrion from the previous winter, grasses, sprouts, sedges, moss, and forbs are the principal sources of food for brown bears worldwide in the spring. In the summer and the first few weeks of fall, fruits, and notable berries, assume a greater significance. If fruit yields are weak, roots and bulbs become crucial in the fall for some inland bear populations.

13. Adult bears are generally immune to predatory attacks except for large Siberian tigers

Except for enormous Siberian (Amur) tigers and other bears, adult brown bears are typically resistant to predatory attacks. While brown bears are typically killed by tigers in conflicts over prey or as a form of self-defence, brown bears have also been known to kill female tigers and cubs outside of their dens. Tigers mostly go after a bear’s fat reserves, which include the back, hams, and groyne. Because brown bears cannot climb trees and live in more open settings than black bears, they are more frequently attacked by tigers than black bears.

Brown bear behaviour can be affected by the presence of tigers; while some bears exhibit little fear, others follow tiger tracks to scavenge kills or may even attempt to prey on tigers. Even though they face predators, some brown bears gain from taking tiger prey. Brown bears will occasionally take from tigers and leopards, killing large animals in the process.

14. The brown bear has a naturally long life

The brown bear lives a long life by nature. The oldest known age for the reproduction of any ursid in the wild is 28 years old when females have been seen reproducing. Females can reproduce at their prime from the age of four to 20. Within populations that are only occasionally hunted, brown bears of both sexes are thought to live for an average of 25 years.

The oldest known wild brown bear was around 37 years old. While males in captivity have been confirmed to live up to 47 years, with one captive male perhaps reaching 50 years of age, the oldest known female in captivity was close to 40 years old. According to a study conducted in the Greater Yellowstone Ecosystem, female grizzly bears have a higher annual survival rate than males within wild populations, even though male bears may live longer in captivity.

In most protected locations, the average annual mortality rate for bears of any age is believed to be 10%; but, in hunted populations, the average annual mortality rate is estimated to be 38%. Even in well-protected habitats, 13% to 44% of cubs die during their first year. In any particular year, cub mortality rates of 75–100% are not unusual. Beyond being eaten by large predators like wolves, Siberian tigers, and other brown bears, kerbs also perish from malnutrition and accidents.

15. Brown bears seldom attack humans on sight and usually avoid people

According to estimates, 1 in 1000 foot-to-foot contacts with brown bears in Russia end in an attack. However, due to their unpredictable disposition, they have the potential to attack if startled or threatened. In North America, there are typically two fatal bear assaults per year. Since 1902, there have only been four fatal bear encounters in Scandinavia that are known to have occurred.

Bear assaults are most frequently sparked by surprise and curiosity. When in pursuit of food, some bear species, such as polar bears, are more inclined to attack people; on the other hand, American black bears are much less likely to do so. Polar bears rarely attack humans since they are infrequently seen in the Arctic Sea, despite their bravado and potential for predation if the bear is hungry.

There are various selection factors that support aggressive conduct in brown bears. Brown bear females who are more aggressive are also better able to ensure that their cubs live to adulthood. In North America, mothers protecting their children are the most likely to attack, resulting in 70% of all brown bear-related fatalities involving humans.