【Sexy Sisters】

The Sexy Sistersfat bears exemplify success.

Many of the brown bears at Katmai National Park and Preserve have put on hundreds of pounds this summer as they've devoured bounties of 4,500-calorie salmon. Their goal is to outlast the long-winter famine by surviving off their fat stores during hibernation, and many succeed.

Their natural triumph is already conspicuous in early September 2021, about a month before the park holds its annual Fat Bear Week contest, and some two months before hibernation begins. That is to say, many bears are already impressively fat, and will still grow fatter.

Footage from the explore.org bear cams (which livestream Katmai's bears along the park's fish-filled Brooks River) shows the profound size of some of the river's more dominant bears, which earn access to the river's most fruitful fishing spots. But pretty much all these Katmai bears are looking "healthily pudgy," Mike Fitz, a former Katmai park ranger and currently a resident naturalist for explore.org, told Mashable.

The first video below shows perhaps the largest bear of the river, the aptly-numbered bear 747, who won last year's Fat Bear Week contest. He's the rotund bear on the right.

"He's a tank once again," said Fitz

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At Katmai, the brown bears largely feast on sockeye salmon, which spend two or three years at sea (themselves fattening up on tiny sea creatures) before returning to the streams they were born in to create new generations of salmon. This is the annual salmon run. Typically, the prodigious run up Katmai's Brooks River ramps up in early July. This year, it kicked into gear in late July, but was a strong run, noted Fitz. Now, the bears are still feasting on later runs of a different salmon species, called silver, or coho, salmon.

Fat Bear Week kicks off on Sept. 29. In this celebration of conservation, biodiversity, and all of Katmai's bears, you'll be able to vote online in a playoff-style tournament for who you think is the fattest bear. The big boys, like those in the videos above, are already huge.

But the competition will be stiff. The bear 128 ("Grazer") and her yearling cubs (yearlings are back for their second summer) have expertly caught and feasted on salmon atop the Brooks River waterfall this year. They've also fattened up, and promise to be formidable contenders.

"She and her yearlings are huge," said Fitz.

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