There are many many species of ';squirrels';. To which of them are you referring? Their litter size (and nesting habits) varies widely both within and amoung species.How often do squirrels have babies - on average how many babies?
Typically common red/grey/black squirrels have 2 litters a year, once in the spring and once in the fall. That way they have time to raise the first litter to independence, and then raise the second before hibernation. They raise the babies in their nests, where they are also born. Not too sure on the size of the litters.
They seem to have babies often with litters around 5 to 6
They have litters like kittens. They keep them there in the nest. They don't move them. They have a parent watch the nest, while the other finds nuts and other sources of food.