 Nests are roughly spherical and a small platform often extends beyond the bowl edge on one side.The nests are used year-round by most Abert's squirrels for nightly shelter, although females often move the litter to a larger nest when the young are 3 to 6 weeks old.In winter, pairs of Abert's squirrels, usually an adult female and one subadult (presumed) offspring, use the same nest for shelter.