The fundamental social bond in Richardson’s ground squirrels is between mother and offspring. Because sons generally disperse whereas daughters settle near their natal site, in effect the fundamental social unit is based on lifetime associations between mother-daughter and littermate sisters. Female Richardson's ground squirrels tolerate the proximity of closely related female kin, including their mother, sisters, grandmother, daughters, granddaughters, aunts, nieces and cousins. Female ground squirrels recognize their kin throughout their life, even after many months without contact such as during hibernation. Female ground squirrels are antagonistic towards all other squirrels, regardless of sex.
Although close female kin tolerate each other’s nearby presence, this tolerance does not extend to sharing the nest in which young are born and reared. During pregnancy each female establishes her own burrows system with 2 or 3 nest chambers in which she rears her offspring. Thus, for the first month of life infants come in contact only with each other and with the mother.
Typically, the interactions between familiar kin are more amicable and less antagonistic than interactions between unfamiliar nonkin. Juvenile siblings play together and may even sleep communally for a time, but these amicable interactions decline as the juveniles get older. Even so, juvenile females remain physically close to and amicable with their sisters and mother throughout life. (see Social Organization)
The main association between adult male and female ground squirrels is courtship and copulation. Females are in estrus for a few hours on one afternoon of one day of the year, during which time they tolerate the proximity of males. Thereafter, once the female is pregnant, she is intolerant of the proximity of any male, including her mate(s). There are no lasting pair bonds between adult males and adult females. (see Reproductive Behaviour)
Except for the brief time as juveniles,
all male-male interactions in Richardson's ground squirrels are antagonistic,
involving fights, chases and sparring. Aggression between adult males
is most intense during the mating season in spring. Male ground squirrels
form no social associations, either with other males or with females, and
take no part in raising offspring.