Cast Your Vote for the Chunkiest Alpine Rodent During Colorado’s First-Ever Fat Marmot Week

The inaugural competition puts eight yellow-bellied marmots head-to-head while shining a light on the science behind their seasonal weight gain and survival at high elevations

Sarah Kuta | Daily Correspondent

August 25, 2026 3:33 p.m.

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Fat Bear Week has become a beloved annual tradition, drawing millions of fans who tune in each fall to celebrate the hefty brown bears of Alaska’s Katmai National Park and Preserve.

Now, Colorado is putting its own spin on the popular online event with the launch of Fat Marmot Week, shining the spotlight on the sturdy, high-elevation rodents as they fatten up for hibernation.

Voting opened August 24 and continues on August 26 and August 28, with eight chunky marmots going head-to-head in a tournament-style bracket. The rodent with the largest estimated weight will be announced on August 29, followed by the winner of the popular vote on August 30.

Fat Marmot Week is being run by a team of researchers at the Rocky Mountain Biological Laboratory (RMBL), a nonprofit research hub located 9,500 feet above sea level just outside of Crested Butte, Colorado.

Since 1962, scientists have been conducting the RMBL Marmot Project, one of the longest-running studies of individually marked wild mammals in the world. They’ve been studying yellow-bellied marmots—a large, loaf-sized ground squirrel found throughout the Intermountain West—in a bid to understand their behavior, relationships and adaptations that allow them to survive in harsh, high-elevation environments.

Yellow-bellied marmots are stocky rodents with reddish-brown fur covering their upper bodies and lighter-colored bellies. These tubby critters can weigh up to 11 pounds and measure more than two feet long—about the size of a small house cat—making them a calorie-rich prize for coyotes, grizzlies, golden eagles and other predators.

These social mammals are known as “whistle pigs” for the high-pitched vocalizations they make to warn their colony members of nearby foes. A colony—also called a madness—usually consists of one highly territorial male, several females and any pups born that year. During the warmer months, they can often be found sunbathing on rocks.

Yellow-bellied marmots are mainly herbivores that spend the short alpine summers feasting on grasses, wildflowers and seeds, trying to gain as much weight as possible before winter sets back in. When temperatures start to drop in the fall, they head into their underground burrows, where they undergo a true hibernation: Their heart rate slows to just a few beats per minute, their metabolism drops and their body temperature plummets to as low as 41 degrees Fahrenheit. They can remain in this state for up to eight months, safely tucked underground until spring, when the snow begins to melt and green vegetation reappears in the high country once again.

Researchers say this sets marmots apart from the grizzlies of Fat Bear Week, which do not truly hibernate but, rather, enter a sleep-like state known as torpor.

“You pick up a hibernating marmot and it’s this fuzzy ball and it feels like a cold rock with fur,” Dan Blumstein, an ecologist and evolutionary biologist at the University of California, Los Angeles who co-directs the RMBL Marmot Project, tells the Associated Press’ Brittany Peterson and Mead Gruver. “It’s completely surreal.”

But human-caused climate change seems to be threatening the furry creatures’ survival. This past winter, for example, scientists estimate that nearly two-thirds of one population in Colorado died while hibernating.

“We had over 160 animals, and we ended with 60,” Blumstein tells the AP. “Most of them died because of the lack of snow cover.”

Snow is important for the creatures because it blankets their burrows with an insulating layer that helps keep temperatures inside from dropping too low, per the outlet. But the winter 2025-26 was Colorado’s worst snowpack year on record, and researchers suspect many of the animals froze to death. The lack of snow also left marmots exposed to predators for longer and affected the wildflowers they depend on for food, reports Cormac McCrimmon for Rocky Mountain PBS.

Scientists launched Fat Marmot Week to raise awareness about the animals’ plight, while also soliciting donations for their research, which has been affected by federal funding cuts. The same group has been sharing uncensored, G-rated marmot videos on the adult content platform OnlyFans, raising funds through a tongue-in-cheek account called OnlyMarms. The researchers also partnered with the Colorado brewery Denver Beer Company, which created the limited-release OnlyMarms Extra Thicc Double IPA and is donating a portion of sales to the Marmot Project.

So far, the OnlyMarms account has raised about $6,700, reports the Denver Post’s Tiney Ricciardi. But transaction fees from a marmot-themed, meme-based cryptocurrency called $OnlyMarms have also generated around $100,000, per the AP.

“It’s exasperating to have to go to OnlyFans to raise money for basic long-term ecological research,” Blumstein tells the Colorado Sun’s Betsy Welch. “But it has helped.”

In addition, he says, the publicity OnlyMarms has generated has been “priceless.”

“More people recognize the value of long-term ecological research and basic research in general,” Blumstein adds. “It’s not just about marmots. It’s about the value of basic research.”

Sarah Kuta is a writer and editor based in Longmont, Colorado. She covers history, science, travel, food and beverage, sustainability, economics and other topics.