How would you like to eat and sunbathe all day during the summer and then sleep through the cold winter months? The yellow-bellied marmot of the high regions of Colorado and the West do just that. At up to two feet long and weighing 15 pounds, they are the biggest of the squirrel family and live at high elevation between 6,500 feet and 13,500 feet.
Yellow-bellied marmots are very social creatures. One male marmot protects a colony of up to two dozen marmots, with multiple female breeding partners. Females generally give birth to one litter of 3-8 young each year and the colony raises the young jointly. Only about half of the litter live to be yearlings. The young stay with their mother throughout the first summer, and occasionally hibernate with her.
After their first hibernation, the young male marmots will roam away from their original colony and begin digging their own burrow. They then begin looking for females and may have up to four females living in his colony by the end of his first summer!
Marmots can live up to 15 years, and they hibernate for over half of their life. From September/October to April/ May, they huddle together in their burrows to keep warm. Their heart rate and breathing slows down to help them survive through the long winters at high altitude. They lose almost half their weight during hibernation, so they have a lot of fattening up to do over the summer.
After a long hibernation, marmots spend the spring and summer building fat stores for the next winter. They work as a team to find food ranging from grasses and roots to flowers and the occasional bird egg. One marmot is designated as the “lookout” and actively protects the others while they are eating, sunbathing, and burrowing. If a predator is near, the lookout whistles (sounds like a high pitch beep) and the others scurry down the nearest burrow entrance. These large squirrels are also busy in the summer constructing their elaborate burrows, as deep as 15 feet underground.
If you are hiking in the high country this summer, you are likely to hear the marmots’ high pitched noises before you spot them. This high pitched squeal has also given them the common name "whistle pig", which is what they are called by the old time valley locals.
The marmot has the right idea about life: lazy summers spent eating, basking in the sun, and skipping the cold winter months by escaping underground and sleeping it off. Not a bad life.
Kelsey is the Sustainability Programs Associate at Walking Mountains Science Center in Avon. She enjoys hiking in the high country and sunbathing like a marmot.
