Thirteen-lined Ground Squirrel (Spermophilus tridecemlineatus)
Have you ever seen a thirteen-lined ground squirrel? It is a little bigger than a chipmunk and has a pattern on its back that looks like the 'stars and stripes,’ with 13 alternating brown and whitish lines with a row of spots contained in the dark lines. It is also known as the striped gopher (namesake of the University of Minnesota Gophers football team). The interesting pattern on its back camouflages the thirteen-lined ground squirrel from predators in grasses.
This small rodent is usually found in open or mowed areas such as prairies, golf courses, parks, and cemeteries. Its original range was limited to grasslands of the North American Great Plains, but it easily extended its range into new habitat as land was cleared and the prairies disappeared. Today, it ranges from Canada in the north to Texas and New Mexico in the south, and from central Ohio in the east to Colorado in the west.
The thirteen-lined squirrel’s diet is almost evenly divided between grass, weed seeds, crops such as corn and wheat, and animal matter such as caterpillars, grasshoppers, beetles and bird eggs. They often damage gardens by digging burrows and eating vegetables, but the burrowing does help to recycle nutrients to the soil.
 This squirrel is a diurnal mammal and most active at midday and on warm sunny days; it does not usually go above ground on cool, cloudy days. Because they spend most of their lives below ground, they build extensive burrows: hiding burrows that are short, nesting burrows that are larger, and hibernating burrows below the frost line that contain a large nest and a plugged entrance.
Thirteen-lined squirrels are one of very few true hibernators. In late summer they put on a heavy layer of fat and store a little bit of food in their burrow. They enter the nest in late September or early October and curl into a ball. Their respiration rate then decreases from between 100 to 200 breaths per minute to one breath about every five minutes. The body temperature drops to just above freezing and they lose about 1/3 of their body weight. They will emerge in the spring in March or April.
These squirrels often sit up on their hind legs with their nose in the air looking for danger while eating and then dive down into a burrow when danger is sensed. They are preyed upon by hawks, snakes, foxes, coyotes and cats and are often hit by cars. Up to 90% of newborns die from predation before hibernation begins. Once they have reached adulthood, thirteen-lined ground squirrels probably live for only a few years.
Photos by Nate Fuller |
