This fat bear's transformation is absolutely stunning

Surpassing expectations.
 By 
Mark Kaufman
 on 
a young bear cub walking in a river
The scrawny yearling cub of bear 909 spotted in June 2022. Credit: Courtesy L. Law

It's the happiest time of the year — Fat Bear Week! This year's event takes place from Sept. 23-30, and Mashable will be following all the ursine activity. Katmai National Park and Preserve’s brown bears (also known as grizzly bears) spent the summer gorging on 4,500-calorie salmon, and they've transformed into rotund giants, some weighing more than 1,000 pounds. So, the Alaskan park is once again hosting its beloved annual competition to crown the fattest of the fat bears.


The life of a bear cub is terrifying.

Threats abound. From other bears. From the swirling river. From winter. Only around one in three Katmai National Park and Preserve bear cubs survives their first year. The yearling cub (meaning its second year alive) of bear 909, however, has thrived this summer. And the Fat Bear Week photos prove it.

The park's annual contest, which celebrates the impressive fattening and success of these wild Alaskan bears, shows how the animals transformed over the summer, which often means putting on hundreds of pounds. The cub of 909 changed dramatically, from a scrawny creature to a healthy, filled-out bear. You can see the transformation below.


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Many young cubs are aren't capable of much independence. They often aren't standing atop Katmai's famous Brooks River waterfall trying to catch fish. "By August, however, the yearling developed the skills and confidence to catch a few of her own salmon on the lip of the falls—a feat that yearling bears rarely accomplish," explains explore.org, the organization that runs the livestreaming Katmai webcams.

a bear cub walking in a river
Left: June 2022 Credit: Photo courtesy of L. Law
Right: September 2022 Credit: Photo courtesy of L. Law
a bear growing fatter
The impressive transformation of the yearling cub of bear 909. Credit: Photo courtesy of L. Law

There certainly aren't any guarantees in the callous world of bears. But, with the help of her mother, this yearling cub has put herself in good position to again survive half a year of hibernation, wherein she must rely on her fat stores to survive the winter famine. It's an arduous task that these bears must repeatedly prepare for.

"During hibernation, bears will not eat or drink and they will lose one-third of their body weight," Katmai's ranger's told Mashable. "Their winter survival depends on accumulating ample fat reserves before entering the den. Katmai’s brown bears are at their fattest in late summer and early fall after a summer spent trying to satisfy their profound hunger."

"Each bear faces its own challenges in order to gain the body mass necessary to survive," Katmai's rangers added.

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Brown bears at Katmai typically spend two years with their mother. After awaking from hibernation next spring (in 2023), the sow 909 will likely emancipate this young bear, which means separating from her offspring. The bear will be a subadult, or "teenage" bear, fending for itself in a hypercompetitive bear world.

This bear, not yet given its own number by the park's bear biologists, will fend for itself. It'll be a daunting few years. It won't usually have access to the best fish fishing spots; large, assertive boars and sows (adult male and female bears) will tussle for those prime fishing holes. Yet, like other subadults, this bear will find ways to catch fish, or at least the discarded scraps caught by more dominant bears. And if these summer's transformation is any indication, the young bear has already developed the skills and confidence to amass fat, and boost her odds of survival, in a wild, unforgiving land.

Topics Animals

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Mark Kaufman
Science Editor

Mark was the science editor at Mashable. After working as a ranger with the National Park Service, he started a reporting career after seeing the extraordinary value in educating people about the happenings on Earth, and beyond.

He's descended 2,500 feet into the ocean depths in search of the sixgill shark, ventured into the halls of top R&D laboratories, and interviewed some of the most fascinating scientists in the world.

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