“Fat Bear Week” looks to raise awareness about how bears are adapting to climate change in Alaska’s Katmai National Park and Preserve.
* Fat Bear Week is an annual competition where fans vote for the fattest bear at Katmai National Park and Preserve.
* The event runs from Sept. 23 to Sept. 30, with daily voting on the explore.org website.
* This year’s competition includes returning favorites like Grazer and Chunk, as well as new contenders.
* On Sept. 26, four bears vie for votes and a spot in the semifinals, which begin on Sept. 29.
The chunkiest challenge of the year is here — Fat Bear Week.
Each year, the burly brown bears of Katmai National Park and Preserve in Alaska capture global attention in a March Madness-style bracket challenge as fans pick which bear advances in each round. The 2025 competition began on Sept. 23.
“The bears have been working so hard all season long to get fat,” Sarah Bruce, a park ranger at Katmai, told USA TODAY.
For good reason. For them, bulking up is a matter of life and death.
Here’s why and what else you should know about Fat Bear Week 2025.
When is Fat Bear Week?
Fat Bear Week runs Sept. 23 through Sept. 30. Each day, from noon until 9 p.m. ET, fans can vote for their picks on the event’s website.
The competition received more than 1 million votes last year. There have already been nearly 975,000 votes cast this year ahead of Sept. 26 matchups.
Which bears are in Fat Bear Week?
This year’s contestants are a mix of returning favorites and new contenders.
Returning favorites include 128, nicknamed Grazer, and 32, nicknamed Chunk. Fans can vote for Grazer on Sept. 26. Chunk has already earned a place in the Sept. 29 semifinals.
“[Chunk] sustained a jaw injury this year, and so seeing him still get fat even though he’s been injured is like, ‘Good for you'” she said.
New contenders include bear 602, which Explore.org says has “a peculiar stomping dance that he displays in moments when his excitement level appears to be high,” and Bear 26, who’s believed to be the daughter of former Fat Bear Week champion 435 Holly.
“They’re looking very fat. All of them are,” Bruce said.
What bears won Fat Bear Week yesterday? Results from Sept. 24
Here are the results after Fat Bear fans cast their votes on Sept. 25:
Bear 128’s Yearling: 33,271Bear 602: 117,284 (Winner)
Bear 901: 45,92932 Chunk: 108,482 (Winner)
What bears are competing in Fat Bear Week voting on Sept. 26?
Today’s match features four bears.
Bear 128, nicknamed Grazer, and Bear 909 go neck-to-neck in one matchup in Sept. 26 voting, while Bear 910 and Bear 856, nicknamed Chunk, squabble in the other matchup in the Fat Bear Week tournament.
How to vote for your favorite Fat Bear Week contenders
Eager to vote for your favorite Fat Bear? It’s really easy.
Voting is closed on Sept. 27 and 28. The competition picks back up again on Monday, Sept. 29.
What kinds of bears live at Katmai National Park?
Katmai is known for its iconic brown bears, but their health is intrinsically tied to another species: sockeye salmon.
“We’re really lucky, in this part of the country, to have the most sustainable sockeye salmon run in the world, and we still have these intact ecosystems where humans have developed with the ecosystem instead of humans manipulating the ecosystem to fit our needs,” Bruce said, crediting tribal partners and Indigenous knowledge for sustaining the ecosystem for thousands of years.
“There’s so much to learn about Katmai, and bears are just the tip of the iceberg.”
Who won Fat Bear Week 2024?
Grazer won Fat Bear Week 2024 and 2023.
Bruce noted that 128 was the first female bear to be raising a cub when she won.
Why do bears get so fat?
Bears pack on pounds to prepare for hibernation. They need the fat reserves to survive the long winter.
“Right now they’re in a phase called hyperphagia, and it’s where the hormones in their body have turned off to tell them that they are full,” Bruce said. “They cannot feel fullness no matter how much they eat, so they just keep eating.”
That fat is especially important for females, or sows.
“A female bear will only have a successful pregnancy if she’s fat enough,” Bruce said, explaining that a fertilized egg won’t even implant unless there’s enough fat to sustain the pregnancy. “We have a lot of really fat, heavy single females right now, so we’re hoping for a little bit of a cub boom in the spring.”
Fat Bear Week 2025 livestream
Fans can see some of the bears on webcam at Explore.org, which offers a mix of live video and prerecorded highlights from Brooks Falls.
Fat Bear Week is a partnership between the national parks, Explore.org and the Katmai Conservancy.
