Though they appear to live communally, a population of Richardson’s ground squirrels has a distinct social organization based on female kinship.
Female Richardson's ground squirrels tolerate the proximity of closely related female kin, but are generally antagonistic towards all other squirrels. (see Kinship) This differential response to kin and nonkin creates mother-offspring clusters. Richardson's ground squirrels do not defend a communal territory, rather each individual independently exhibits dominance over intruding nonkin. Although females are tolerant of kin, this does not extend to sharing the burrow system in which they rear their offspring. Each female has her own burrow system in which she gives birth and which she defends even from her closest kin. However, after litters emerge above ground they may intermix if their mothers are kin.
Male Richardson's ground squirrels form no social associations with either sex. After the mating season, males restrict their movements to a smaller area, due in part to the aggressiveness of pregnant and lactating female ground squirrels. (see Habitat and Range and Reproductive Behaviour) At no time are males dominant over females even though they are physically larger than females.
When they first emerge, juvenile
siblings play together and may even sleep communally. But by the
age of 12 weeks, juvenile ground squirrels are behaviourally indistinguishable
from adults both in their social interactions and use of space.