Description.—The yellow-bellied marmot is similar to the woodchuck but is slightly larger. It is decidedly paler in color, less reddish, but possesses white-tipped hairs on the dorsal surface, as does the woodchuck. The yellow-bellied marmot also differs from the woodchuck in having a distinct white bar on the nose. Its pelage is coarse and rather thin.
The yellow-bellied marmot is typically an animal of the basalt talus of eastern Washington but occurs in mountainous areas in northeastern Washington. These animals are usually found near streams, ponds, lakes, or rivers. They wander considerably, however, and are often found far from water. Their wandering habits probably account for their presence near temporary streams and ponds on the Columbian Plateau. When these temporary sources of water dry up in July or early August, the marmots go into hibernation. [Edson] (1935: 68) records a marmot from Bellingham, Whatcom County, far west of the usual range of the species.
The "ground hog" is often hunted for sport and sometimes for food. Near centers of human population the yellow-bellied marmots are extremely shy. Along the highways of the Columbia River on any Sunday in June, it is not unusual to see a dozen cars in an hour, moving slowly past a talus slide while eager hunters scan the rocks for marmots. In the late afternoon, when the marmots leave the protection of the talus slides to drink at the river, they fall easy prey to rifles with telescope sights. Near cities in eastern Washington yellow-bellied marmots have become partially nocturnal.
[Couch] (1930: 2-6) attempted to excavate several dens of yellow-bellied marmots, but decided to leave the task "to some future road-building crew." Embryos found by [Couch] numbered three to six. [Couch] thought the young were born about March 15 in the Snake River area and about April 15 in the upper Okanogan area. The young appear above ground approximately 30 days after birth.
The yellow-bellied marmots enter aestivation from late June to early August, depending on the locality and local conditions. They are active longer in northeastern Washington. [Couch] records a yellow-bellied marmot seen in Okanogan County on October 10, but regards this as exceptional. The marmots near Wenatchee, Chelan County, emerge from their burrows in early March (March 5 to 10, from reports of residents in 1937, 1938). [Couch] (1930: 5) gives February 20 to March 15 as the date of appearance.
A principal requirement for marmots is the presence of rocks. At Cle Elum, Kittitas County, I took a marmot from an alfalfa field where a farmer had placed all the surface stones in a loose pile. Fifteen miles east of Tonasket, Okanogan County, marmots were living in the stones piled by road builders to support the ends of a small bridge. A hundred feet away another marmot was living under an abandoned building. A high, convenient rock near their burrow serves the yellow-bellied marmots as a look-out post. These look-out posts seem, in many cases, to have been used by many generations of marmots, for their feces sometimes fill nearby crevices to a depth of several feet and cover the look-out rock itself. The glacial boulders on the plateau between the Okanogan River and Omak Lake, Okanogan County, furnish the best examples of look-out posts. These numerous isolated boulders, ten to fifty feet in diameter and ten to thirty feet high, each seem to furnish shelter to one or more marmots. Well-worn trails lead from the boulders to burrows and feeding areas.
The food of the yellow-bellied marmot includes grasses and succulent plants found in their habitat. Fondness for alfalfa makes them a serious pest in some areas, for their large size enables them to make considerable inroads on a field. Natural enemies probably include most larger predaceous mammals. Hawks and eagles probably kill their young. Near Tonasket, Okanogan County, Robert [Dalquest] surprised a coyote as it ran across a small wash. A shot caused the coyote to drop a half-grown marmot which it had been carrying.
Marmota caligata cascadensis [Howell]
Hoary marmot
Marmota caligata cascadensis [Howell], Proc. Biol. Soc. Washington, 27:17, February 2, 1914.