Small Mammals of North Dakota
Thirteen-lined Ground Squirrel
Spermophilus tridecemlineatus
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The thirteen-lined ground squirrel is the most common ground squirrel in North Dakota and can be found statewide. Like other species, it prefers well-drained soils for digging burrows and can be found in pasture land, along roadsides, golf courses, and the edges of farm fields.
This is the smallest of the ground squirrels that lives in North Dakota. It has an overall measurement of about 9 1/2 inches of which one-third is tail. Weights may vary from season to season. Spring weights are roughly one-quarter pound whereas fall weights approach half a pound, as they prepare for winter.
As in the Richardson's ground squirrel, the external ear is small. The colorful coat, however, should set this ground squirrel apart from the others. An alternating pattern of dark brown and yellowish-tan stripes extend down its back. The dark stripes contain evenly spaced white dots throughout. The sides and belly are yellowish white.
Thirteen-lined ground squirrels are primarily solitary but may form loose colonies, but not like the densities found in the Richardson's colony. Population densities may approach ten animals per acre. Burrows descend steeply at first and then level off somewhere between four inches and four feet under the ground. Often, more than one burrow is excavated. Some burrows are used for temporary shelter while others contain round chambers for nesting and food storage. During hibernation, an earth plug may block the burrow's entrance.
Daylight is the only time this small mammal is active. Upon emerging from hibernation in late March or April, they are ready to breed. After a gestation period of about 28 days, a female produces one litter of about 8-9 young. Young emerge from the burrow at the age of one month. In late summer, they disperse to find their own homes.
These ground squirrels are omnivorous, feeding on both plant and animal matter. In the spring, available grasses and roots are eaten. During summer and fall, they feed on insects and seeds as they become available. Occasionally, mice and carrion are consumed.
Any wildlife species that has developed a high birth rate such as the thirteen-lined also experiences high mortality. Flooding may play a large part in limiting numbers along with daylight predators such as hawks, badgers, weasels, snakes, and feral cats.
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