Female Richardson's ground squirrels produce a single litter each year, and if they lose their litter, they are incapable of breeding again until the following year.  They give birth underground after a 23-day gestation period.  The litter is born overnight in the chamber which the female uses for sleeping during late pregnancy.  Litters remain permanently underground for 29-30 days, and the mother is the only ground squirrel who has contact with the infants.  Mothers sleep with their infants at night and visit them several times during the day to suckle them.  Mothers raise the young on their own, with no assistance from the father or any of her female kin.  (see Reproductive Behaviour and Reproductive Physiology)

Litter size at birth is usually 6 to 8 young, but extremes of 4 to 14 have been noted.  Unless the litter is killed by predators such as long-tailed weasels or badgers, most mothers are able to rear all offspring to weaning age.  Consequently litter size at first emergence above ground is also usually 6 to 8 young.

At birth, infants weigh an average of 6.5 grams.  They are hairless with ears and eyes closed, digits fused, and teeth unerupted.  Helpless, they are totally dependent on their mother.

The first hints of fur begin to appear after four days, and foredigits separate at 13 days.  By 15 days of age, the infants begin to look like miniature ground squirrels but they are still incapable of locomotion, and the eyes are still closed.  By 22-24 days, ears and eyes are open, teeth are present, and the fur coat is well developed.

At the age of 29-30 days and weighing between 65 and 85 grams, the young first emerge from their natal burrow.  They immediately begin eating solid food, soon becoming nutritionally independent of their mother.  At 50 days of age, juveniles moult the baby fur and grow in their adult fur coat.  data

Young from large litters are relatively small, yet they emerge above ground at the same age as do larger juveniles from small litters, and make the transition from milk to solid food at the same age.  This indicates that age is a more important factor than size in making the transition to solid food and above ground activity.