Fat Bear Week isn't just fun and games. For these Alaska bears, it's 'all about survival.'

Many people will never get to see Katmai National Park and Preserve's iconic brown bears in person. It's not easy to get to their home on the Alaska Peninsula, and fewer than 25,000 visitors made the trip last year, compared to more than 14 million at America's most visited national park, Great Smoky Mountains. But travelers who make the trek are in for a treat.

"You can see bear behaviors like you would never even imagine," said Keith Moore, an interpretive park ranger at Katmai. "You could spend a lifetime in Yellowstone and still not see as much bear behavior as you could here in just a season."

The bounty of sockeye salmon running in the Brooks River starting in late June and July creates an extraordinary scene around Katmai's Brooks Camp. More than 40 bears can be seen along the 1.5-mile river at the same time, with around 60 spotted simultaneously several years ago, according to Moore.

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"We have an opportunity to watch bears interact with each other and tolerate each other, which they normally don't do, but because of this amazing food source, they're much closer together and we can see their behaviors," he said.

Nature lovers who can't make the trip to Katmai can see the bears via live video and, from Oct. 5-11, cheer them on during the park's annual Fat Bear Week competition.

What is Fat Bear Week?

Fat Bear Week is a March Madness-style bracket challenge that pits some of the biggest bears along the Brooks River against each other in the arena of public opinion. Votes determine the winner.

"It really started out as just celebration of this transformation that our bears go through," Moore said. "You know, over the course of a few months, we'll see these bears potentially double in size in some cases, which is really remarkable."

The bears need that fat to help them survive months of hibernation, during which they'll lose upwards of a third of their body weight.

"So it's really important that they put on the pounds," Moore said.

How does Fat Bear Week work?

Each day starting Oct. 5, the public is invited to vote on a matchup of bears on FatBearWeek.org. Voting is subjective and based entirely on appearance and opinion, not actual weight.

The bears with the most votes advance to the next round until a winner is crowned on Fat Bear Tuesday, Oct. 11.

There's no prize besides bragging rights and perhaps peace of mind.

"I think if we deem a bear the fattest bear, we can all like sleep well at night knowing that bear is going to survive through hibernation," Moore said.

When did Fat Bear Week start?

The first Fat Bear Tuesday was held in 2014.

It didn't become Fat Bear Week until 2015.

Who will win Fat Bear Week?

Regardless of who wins the title, all the contestants are winners for bulking up.

"It's just all about survival," Moore said. "We can kind of have fun with it being like, 'Oh, look how fat this bear is,' but, you know, ultimately, a fat bear is a fit bear."

Who won Fat Bear Week last year?

Bear 480 Otis won Fat Bear Week 2021.

Fat Bear Week's Hall of Champions can be found here.

How do rangers choose bears for Fat Bear Week?

"Typically, we like to include some young bears to give them an opportunity to be seen by the public," Moore said. "And then, of course, we have other bears that are really popular like 435 Holly, 747,128 Grazer ... We like to include those fan favorites while also introducing some new ones every year."

This year's Fat Bear Week contestants can be found here.

Why do only some bears have names?

Moore explained that a previous bear monitor gave some bears nicknames to help identify them.

"We've kind of grandfathered those (names) in, but currently, our bear management plan does not acknowledge the nicknames," he said.

How do rangers tell bears apart?

Bears are identified by visual cues like fur color, scars and even behavior.

"Some bears just behave differently than others, the places that they occupy, the fishing strategies," Moore said.

He noted that identifying by fur color can get tricky because the bears' fur coats change from summer to fall and winter and get darker.

Are Katmai bears grizzlies?

Katmai National Park and Preserve's bears are brown bears, but not grizzlies.

Katmai's website notes their large male brown bears are routinely bigger than grizzly bears at parks like Yellowstone, and grizzly bears tend to live farther inland, without access to coastal foods like salmon.

How many bears live in Katmai?

Roughly 2,200 brown bears are estimated to live in Katmai National Park and Preserve, which at 4.1 million acres, is larger than Yellowstone and Yosemite combined, Moore notes.

He said about 100 different bears use Brooks River each season.

What else is Katmai National Park famous for?

"Believe it or not Katmai National Park and Preserve was established because of a volcanic eruption in 1912," Moore said. "It actually has nothing to do with the bears."

Part of Katmai's mission is to "protect, study, and interpret active volcanism" in the area.

When can you see the bears at Katmai?

Katmai National Park and Preserve is open year-round, but the bears aren't visible all year.

"We typically see the highest concentrations of fish in July, and that's when we see our highest concentration of bears," Moore said of Brooks River. "We see a secondary concentration of bears in September, when they're taking advantage of all the dead and dying fish."

He said the bears begin making their way to their hibernating dens in October in November, sleep until spring, then begin coming out in larger numbers in May.

Is there a Fat Bear Week livestream?

Explore.org operates a web camera near the fall along Brooks River, but it doesn't always show bears in real time. The camera runs on solar power, so it's only live when there's enough sunlight.

When it's dark out, viewers can watch highlight videos of the bears instead.

Are there other cameras in national parks?

The National Park Service and Explore.org offer a host of live cameras across parks, featuring sled dog puppies, eagles, marine life and more.

"To experience a place that not a lot of people get to in person, from the comfort of their own home is really, I think it's pretty amazing," Moore said.

This article originally appeared on USA TODAY: Fat Bear Week at Alaska'a Katmai National Park is a game of survival