The most widely distributed species of bear in the world, the majestic brown bear roams and resides in the forests and mountains of North America, Europe and Asia. Although its range has shrunk due to various threats and local extinctions, its total global population is not under immediate threat with over 200,000 believed to still be living in the wild.
While it is one of the largest living omnivores on Earth, the size of a brown bear varies considerably depending on the season, food availability and which population it is from. The largest of them are found along the coasts of British Columbia and Alaska where they often rival their closest relative, the polar bear, in size.
What Is the Average Lifespan of a Brown Bear?
Brown bears have a naturally long lifespan, living to around 20 to 30 years in the wild. Despite this, most die early with the mortality rate of first-year cubs being particularly high due to malnutrition and starvation among other factors.
Within minimally hunted populations, however, the average lifespan of both sexes is estimated to be around 25 years. Some females in the wild have even been recorded reproducing up to the age of 28 which is the oldest known of any ursid species.
To date, the oldest brown bear discovered in the wild was almost 37 with those in captivity often living even longer on average.
Brown Bear Lifespan in Captivity
In zoos and other carefully managed wildlife conservation facilities, male brown bears have often been recorded living into their 40s. This is because all their needs are met, they don’t have to hunt for food and they are routinely given medical checks.
While one male even attained the age of 50, the oldest captive female on record was 40 years old when she passed away.
The Life Cycle of a Brown Bear
Newborn brown bears are very vulnerable, being blind, hairless and toothless, too. While they only weigh around 350-510 grams at birth, they quickly grow and gain weight over the first six months of their life.
Cubs usually continue feeding on their mother’s milk until spring or early summer. After this, they also forage for and eat other food sources such as berries, grasses and bulbs.
Baby brown bears normally remain with their mothers until the age of 3 or 4 with some becoming independent at just 1.5 years of age. While females mature sexually sometime between the age of 4 and 8, the species keeps growing up until the age of 10 or 11.
Brown bears can grow to a colossal size with males weighing up to 350 kilograms and females 200 kilograms. This varies widely though depending on their subspecies and population and the season of the year.
Brown bears mate from mid-May to early July with the serially monogamous creatures showing no sexual interest in each other outside of this period. Both males and females will try to mate with as many members of the opposite sex as possible during this narrow time frame.
The females become pregnant during their winter dormancy and give birth 8 weeks later while they are still hibernating. A litter usually consists of between 1 and 3 cubs with more than 4 being pretty uncommon.
As the cubs are fully dependent on their mother for the first couple of years, females generally only breed again once their independent offspring have headed off on their own.
Probable Causes of Brown Bear Deaths in the Wild
As the large, ferocious adults have almost no natural enemies, most threats to brown bears occur when they are still vulnerable cubs. Even in well-protected areas, around a third die within their first year with starvation, accidents and predation by wolves, Siberian tigers and other brown bears being the biggest killers.
If they survive the first couple of years, then their outlook is much brighter although malnutrition and attacks by other brown bears can still prove to be fatal.
Besides food scarcity, the most serious threats facing brown bears are either from humans or due to habitat destruction. This is through either legalized hunting or illegal poaching with the wild natural areas available for brown bears to live in sadly being encroached upon and reduced year-on-year.
Oldest Known Brown Bears
Andreas – One of the last dancing bears in Greece, Andreas was rescued and placed in a sanctuary in 1993. He passed away in 2013 at the age of 50 and still holds the Guinness World Record for the oldest brown bear in captivity.
Ginger – The oldest known brown bear to have lived in a North American zoo, Ginger reached the ripe old age of 40. The ginormous grizzly far exceeded the average life expectancy of females in captivity, bringing great joy to everyone who saw her at Columbus Zoo.
Grizzly 168 – First captured and tagged in 1989, Grizzly 168 went on to be the oldest brown bear ever documented in the Greater Yellowstone Ecosystem. After decades spent roaming about amidst the mountains, the withered grizzly was euthanized in 2020 at the age of 34.