Social Spacing & Social System

Columbian ground squirrels live in colonies that can consist of over 100 individuals (Manno 2008). Females live in philopatric kin clusters with a dominant, reproductive male (Manno 2008). Also, within these clusters are members of both sexes that are non-reproductive. These individuals may be juveniles, yearlings, or non-dominant males (Manno, 2008).

These clusters are maintained by a complex social network. Various dyadic relationships maintain the social structure of the cluster (Manno 2008). A recent study has shown that this network is dependent on a few key individuals and may break down with the removal of these individuals (Manno, 2008).

The Columbian ground squirrel’s territory fits the classical territory model. Within their territory are defensible resources, nesting burrows, and burrows for the adult individuals (Manno, 2007). Dominant males will defend their territory against other squirrels and may even attack nesting sites in other territories (Steiner 1972). These attacks will often result in the deaths of juveniles and yearlings (Steiner 1972). If a dominant male enters a neighboring territory, an alarm call will be emitted and he will be treated as a predator (Steiner, 1972).

The Columbian ground squirrel mating system can be classified as hierarchical promiscuity. Every April, male squirrels will emerge from their hibernation burrows. Following them, are the female squirrels just a few weeks later. Mating season typically begins in early May and lasts about a month (Elliott 1991). When the females emerge, they seek out a mate immediately (Manno 2008). Females will most likely breed with the territorial male, but may also copulate with subordinate males and males in other territories (Manno 2008).

Immediately after mating, the male will give a call that is acoustically identical to an alarm call (Manno et al. 2007). This call is emitted to signify that the male is guarding the female and has mated with her. Furthermore, the mate guarding period gives the male’s sperm time to fertilize the female’s eggs. This time is crucial, since the female will mate with the next male she finds (Manno et al. 2007).

Following the mating season, successful females will break off interactions with the males and prepare to give birth to their litter by preparing a nest (Elliott 1991). Females will become very defensive during this time, and may attack males if they approach the nest (Elliott 1991).  

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.