The 2 litters per yr average about 3 young each. Food availability may limit the size and number of litters. Matures at 11 mo. Yearlings generally produce only 1 litter. Hawks and owls are the principal predators.
Snakes prey on young.
Barkalow, F. S., Jr., and M. Shorten. The world of the gray squirrel. J. B. Lippincott Co., Philadelphia and New York. Byrne, S. 1979. The distribution and ecology of the non-native tree squirrels Sciurus carolinensis and Sciurus niger in northern California.