Marmots are among the most commonly seen mammals in the mountains and high deserts of the Pacific Northwest. This is because they are active during the day, like most other members of the squirrel family (Sciuridae). Hikers often encounter these large (up to 30 in long), plump rodents where trails pass through talus fields or subalpine meadows.
The Yellow-bellied Marmot (Marmota flaviventris) is one of four species of marmot found in Washington and Oregon. The Yellow-bellied Marmot– also called the Rockchuck– lives east of the Cascades, in subalpine meadows and dry grasslands where there are piles of big rocks.
Rocks provide protection from predators such as golden eagles, coyotes, and foxes. When threatened, marmots retreat into burrows excavated beneath the rocks.
When not in their burrows, marmots sun themselves on top of rocks or feed on nearby grassy or herbaceous vegetation. Yellow-bellied marmots eat as much as they can in spring and early summer to fatten up for their long annual hibernation. This period of extremely low metabolism begins in late summer for this species. Summer hibernation is called estivation, and is an adaptation for surviving in dry habitats where food and water are scarce in late summer.
The estivation/hibernation of Yellow-bellied Marmots continues through fall and winter, lasting six months or longer! During this time, the marmot’s heart rate slows to only a few beats per minute and breathing is similarly slowed down.
Yellow-bellied Marmots live in colonies of up to 20 individuals and have a hierarchical social structure. Dominant males are at the top of the hierarchy and occupy the choicest burrows in the local habitat.
If you have come across marmots, you have probably heard the sounds they make to communicate with each other. Marmots whistle or chirp to alert their colony-mates to potential threats. They have a variety of different calls, each meaning something different.
The fur on the Yellow-bellied Marmot’s belly is indeed yellowish, which distinguishes it from the Hoary Marmot (Marmota caligata), which has a gray belly. The Hoary Marmot lives at high elevations in the Washington Cascades.
I saw the marmot in the photo above on the Swale Canyon portion of the Klickitat Trail in Washington. There is a large colony of Yellow-bellied Marmots scampering around the rocks along the trail. They feed on the hillside south of the trail and bolt for their burrows when approached.