Thirteen-lined squirrels (Ictidomys tridecemlineatus formerly Spermophilus tridecemlineatus) are small ground squirrels found in well-drained grasslands. They derive their name from the thirteen stripes on the length of their body. These stripes alternative between light and dark and some are spotted. They are rather small only 7-12.5 inches long (nose to tip to tail).
Thirteen-lined ground squirrels can be found in grasslands occurring between Ohio and Montana and Alberta and Texas. In other words, what used to be known as the Great Plains. Thirteen-lined ground squirrels prefer short-grass as tall grass prevents their ability to see oncoming predators.

Like other ground squirrels, thirteen-lined ground squirrels hibernate for periods longer than they are active. Emergence from hibernation varies by latitude and elevation. For example, Colorado thirteen-lined ground squirrels emerge from hibernation between April 1 and April 15. Ground squirrels begin hibernation as sunlight begins to diminish. Males usually enter first in July, followed by females in July-August and young in September. These timings likely are due to the greater need for females and young of year to pack on fat lost due to raising young (females) and need for extra time (young of the year). As a rule, males emerge from hibernation before females and mating occurs quickly. Males do not assist in raising young.

The diet of thirteen-lined ground squirrels consists primarily of seeds. In fact, the term “Spermophilus” which was the genus of their former scientific name means seed lover. Ground squirrels can cause localized damage to crop growers as they pluck the seeds from the ground following planting. But thirteen-lined ground squirrels also have a taste for protein. They are significant predators of insects, such as grasshoppers and the butterfly larvae. In fact, researchers believe that ground squirrel feeding on insects actually compensates the farmers for losses in seeds. But ground squirrels have also been known to eat bird eggs, small birds and chickens, and even snakes. So, while ground squirrels are identified as vegetarian, they are not pure vegan.

Most people hate thirteen-lined ground squirrels because of the holes they make in their lawns. In fact, out of 65 burrows, ground squirrels can have 100 holes. Yet of those burrows, only 22% actually extend below the frostline to a den. The rest of the burrows are hideaways that thirteen-lined ground squirrels use to escape predators and other dangers.

Hopefully this information will help appreciate this important animal in our landscape. If you live in their range, look for them on bright, sunny days when the wind is lower than 15 mph and the temperature is above 50 degrees F. Information on control will wait for another blog, but if you need it sooner, visit https://www.academia.edu/20176531/Thirteen-lined_Ground_Squirrel_Controlling_Damage

Source: Streubel, Donald P. and Fitzgerald, James P. 1978. Spermophilus tridecelineatus. Mammalian Species 103(Sept):1-5.