Predation

The Columbian ground squirrel faces a large number of predators from both the ground and air. Predators on the ground consist of: brown bears (Ursus arctos), coyotes (Canis latrans), marten (Martes Americana), badgers (Taxidea taxus), lynx (Felis lynx), weasels (Mustela), and mountain lions (Felis concolor) (Elliott 1991). There are also numerous avian predators such as: golden eagles (Aquila chryaetos), red-tailed hawks (Buteo jamaicensis), and goshawks (Accipiter gentilis) (Elliott 1991).

Only predation by badgers has been studied in depth, in regards to its effects on the Columbian ground squirrel (Murie 1992). Badgers tend to attack juveniles in the nest. They do this because the young squirrels have not yet developed the ability to recognize and avoid predators (Murie 1992). Badgers have a significant effect on the population of the ground squirrels. Nests that got attacked only had one or more juvenile emerge 41% of the time (Murie 1992). In one year, badger predation eliminated 56% of the juveniles born (Murie 1992).

Due to the very high predation risks, Columbian ground squirrels have been forced to develop different ways to avoid predators. One such way is their alarm call system and close social quarters (Dobson and Fairbanks, 2007). The close quarters that the ground squirrels live in allow them to quickly spot predators and issue an alarm call that will warn other of the presence of the predator (Dobson and Fairbanks, 2007).

The simplest explanation for the close living quarters is that this is selfish behavior. The close quarters supports the “selfish herd” theory, because when a predator is in the area, each individual squirrel has a significantly lower risk of being taken, rather than if it were alone. The alarm calls could be interpreted as an altruistic act. The squirrels rely on one another to warn the group of the presence of a predator. The squirrel issuing the call will not only benefit the group by warning them, but will also benefit in the future when another squirrel spots a predator and issues an alarm call.

This website was completed in partial fulfillment of the requirements for Biology 323, Animal Behavior, at Davidson College in the Spring Semester 2008.

Please send any comments, questions or suggestions regarding this website to Kevin Cook or Professor Verna Case.