Voting ends Tuesday in the annual Fat Bear Week contest at Alaska’s Katmai National Park and Preserve, with viewers picking their favorite among a dozen brown bears fattened up to survive the winter.

The contest, which is in its 10th year, celebrates the resiliency of the 2,200 brown bears that live in the preserve on the Alaska Peninsula, which extends from the state’s southwest corner toward the Aleutian Islands. The animals gorge on the abundant sockeye salmon that return to the Brooks River, sometimes chomping the fish in midair as they try to hurdle a small waterfall and make their way upstream to spawn.

The bracket this year featured 12 bears, with eight facing off against each other in the first round and four receiving byes to the second round. They’ve been packing on the pounds all summer.

Adult male brown bears typically weigh 600 to 900 pounds in mid-summer. By the time they are ready to hibernate after feasting on migrating and spawning salmon — each eats as many as 30 fish per day — large males can weigh well over 1,000 pounds (454 kilograms). Females are about one-third smaller.

When fans vote in each round, they aren’t only considering the bear with the biggest belly. Bear fans have been instructed to vote on the ursine that they believe “best exemplifies fatness and success in brown bears.”