Belding’s ground squirrel (Spermophilus beldingi) is a diurnal rodent that lives in alpine and sub-alpine meadows, pastures, and croplands in parts of California, Oregon, Utah, Nevada, Idaho,and Washington. These squirrels are typically found at higher altitudes, such as in the Sierra Nevada Mountain Range, and also in the Cascade Mountain Range. Because Belding’s ground squirrel lives at high altitudes, it must hibernate for a large portion of the year to avoid the severe winter weather. As a result, these squirrels hibernate for almost eight months out of the year, and are only above ground for 4 months.

Belding’s ground squirrel utilizes a home range so that it has enough space to find plenty of food to add to its fat reserves. Females will also defend a nesting only territory from other squirrels while she is pregnant and lactating. Female kin will often help each other defend these territories, and will allow each other access to their respective territories (thus, female with kin use less energy to establish and defend nesting-only territories). This joint defense helps females protect their litter from infanticide (which is the killing of infants by a member of the same species). Male squirrels do not defend any territories. In fact, males are highly mobile. Late in their juvenile spring, male Belding’s ground squirrels leave their natal area and disperse to a new colony. This is a very dangerous time in a male’s life because they are totally solitary and are exposed to predators. When they arrive at a new colony, they will establish a burrow in between the nesting territories of the females.

Because of the extreme environment that they inhabit, and the extraordinarily high predation rate, Belding’s ground squirrels have developed several fascinating behaviors to help them deal with selection pressures. First, Belding’s ground squirrels have two different alarm calls, trills and whistles, which alert others to potentially dangerous (terrestrial) predators and immediately dangerous (aerial) predators, respectively. Female ground squirrels with near-by kin are more likely to give trill calls, suggesting that alarm calls are nepotistic (have evolved so that kin may have better reproductive success, passing the “family genes” on to the next generation). Belding’s ground squirrels are also very dependent on their burrows for predator protection. When a whistle call is sounded, squirrels will run back to their burrow for protection.

In the four months they are above ground, Belding’s ground squirrels much accomplish what other animals do in a full year, AND gain enough fat reserves to last them through the winter. Thus, the squirrels must be ready to breed soon after they emerge from hibernation (in February thru April, depending on the altitude). Males emerge from hibernation first, followed by the female in a week or two. Mating begins almost right away. Belding's ground squirrels are very promiscuous. A female is only receptive during a 4-5 hour stint, one afternoon of the year. When she is receptive, excited males will gather around her, and will fight each other violently (often to the death) for access to her. She will mate with the male that wins, and will also seek out approximately 5 other “champion” males to mate with (thus, Belding’s ground squirrel litters are often multiply sired). After mating, the males will again disperse.

The pregnant female will dig a nesting burrow, create a grass nest inside of it, and then defend the territory surrounding against other squirrels. After approximately 25 days, she gives birth to a litter or 3-8 pups. These pups stay in the burrow for 27 day, and then will emerge from the burrow. During the next few weeks, the juveniles will learn how to correctly respond to alarm calls and will be able to recognize familiar individuals. Later in the summer, the male juveniles disperse and will move to new colonies, possibly to prevent inbreeding. Female juveniles, on the other hand, settle in burrows near to their relatives.

Obviously, Belding’s ground squirrels are fascinating, complex rodents that are highly adapted to their niche. Belding’s ground squirrel have many behaviors that are interesting to scientists, including the development of their alarm calls, their nepotism, the development of kin recognition, and the physiology surrounding their hibernation. Future studies centering on Belding’s ground squirrels are sure to uncover more fascinating information and will possibly even unlock clues to evolution of Spermophilus beldingi, and the adaptability of their behaviors.

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***Note: This page was created by a student for an undergraduate class (Animal Behavior, BIO 323)
 at Davidson College***