Many varieties of seeds and berries furnish the food supply of this animal, and quantities are stored in their burrows for use during the spring and early summer. Although the chipmunks hibernate during most of the winter, they sometimes venture out on warm, spring-like days, returning to their winter nests when the weather again becomes inclement.
Predaceous birds and mammals active during the daylight hours are all enemies of the chipmunks. These natural enemies work to keep the chipmunk populations free of contagious diseases such as relapsing fever, which is transmissible to human beings, by removing sick and sluggish chipmunks before they can infect their companions.
Mantled ground squirrels are popular with park visitors.
CASCADE MANTLED GROUND SQUIRREL, BIG CHIPMUNK
Citellus saturatus (Rhoads)
As the name implies, the mantled ground squirrels are ground dwellers. In general external appearance they resemble the eastern chipmunks, but are considerably larger, and much bigger than their environmental associates, the western chipmunks. They may be further distinguished from the latter species by the more robust body, the conspicuous white eye-ring, and the absence of stripes on the head. The Cascade species of mantled ground squirrel is about twelve inches in length overall, with a flattened, somewhat bushy, narrow tail some four inches long. The sexes are colored alike, the mantle over the head, sides of the neck, shoulders, and forearms is reddish-brown, mixed with black, which is in distinct contrast to the rest of the upper parts. The back is grizzled black, merging into grizzled red-brown over the rump, with a narrow yellowish-white stripe, edged with black, on each flank from shoulder to thigh. The underparts and the upper surfaces of the feet are yellowish-white. The tail is well-clothed with dark, yellow-tipped hair above, yellowish-brown below.
Specimens in park collection: RNP-33, RNP-34, RNP-36; Longmire Museum, Park Headquarters.
The mantled ground squirrels are found only in western North America, on the forested mountain slopes from California, Arizona, and New Mexico north into British Columbia.
The species common to Mount Rainier National Park is found in the Cascade Mountains of Washington, and on the Mountain it is confined principally to the Hudsonian zone, between 4,500 and 6,500 feet. It is most abundant on the east side, but is very common locally in the Paradise Valley vicinity.
This animal inhabits by preference the rather open, rocky hillsides, and is seldom seen in the heavily forested sections. Burned over brush lands are favored localities, particularly on those slopes exposed to the sun.