There are fat bears in Alaska, and you can vote on your favorite

Every October when the weather turns crisp, thousands around the country tune in to watch a high-stakes tournament play out between fierce competitors, with one eventually crowned champion.

But we're talking about bears, not baseball.

It is, after all, Fat Bear Week.

At Katmai National Park in southern Alaska, brown bears are winding down a stretch of nonstop eating, in which they gain hundreds of pounds to prepare for hibernation. They cavort and dive in Brooks Falls, feasting on migrating sockeye salmon and gaining up to 4 pounds a day.

The National Park Service has capitalized on the increasingly rotund population by livestreaming the hungry bears and creating an online bracket in which 12 of the park's paunchiest are pitted against one another. Fans vote for their favorite bear in head-to-head matchups until the title of Fattest Bear is bestowed, this year on Tuesday.

The tournament has become a social media sensation and has provided a diversion in the midst of a stressful news cycle. The livestream draws hundreds of watchers at a time, and thousands vote and comment on Twitter and Facebook, arguing vociferously over sitting positions and camera angles. “We are all bear 409,” one Twitter user wrote in response to that bear's heft.

The weeklong tournament was started in 2015 by the National Park Service in an attempt to raise interest and educate non-Alaskans about Katmai's wildlife. (The park was established in 1918 and sprawls over 4 million acres but has limited public access - its one established campground allows just 60 visitors per night.)

There are more than 2,000 brown bears in Katmai, and in October and November they enter their dens, where they can hibernate for up to half a year and lose a third of their body mass. To prepare their bodies, they must enter a state known as hyperphagia, in which they eat nearly nonstop until they become practically unrecognizable to the rangers who know them.

In the early summer, their menu options are limited - the omnivorous bears can subsist on sedge and berries. But starting in late June, millions of sockeye salmon swim upstream through the park to spawn. Bears will congregate en masse around Brooks Falls and catch them easily. The prime eating real estate lies just beneath the falls. “The bears will feel around with their feet to grab them,” Sara Wolman, a Park Service ranger at Katmai, said in a phone interview.

A single bear can add up to 4 pounds of weight a day, eating upward of two dozen sockeye salmon - which each contain about 4,000 calories. The largest adult males can turn in for the winter weighing in at more than 1,200 pounds.

The webcams - which provide vivid footage and are controlled by volunteers - have transformed the charismatic bears into social media celebrities. A perennial favorite is Otis, a 22-year-old behemoth who has won the competition two of the last three years. But on Friday he was defeated easily in the second round by a hulking challenger - Bear 409. Nicknamed Beadnose, she won the matchup by more than 3,000 votes and will meet Bear 854, nicknamed Divot, in the semifinals.

“I'm rooting for her,” Wolman said, praising her technique. “She's got her spot on the lip of the falls. She kind of raises her one paw and will just catch them right there.”