Try calling your local wildlife or nature center for information. The squirrels may not be in fact abandoned, the mother may just be away from the nest for a period of time. They will be able to help you discern if indeed they need to be rescued and can tell you how and what to feed them. Frequently KMR ( Kitten Milk Replacer is used..buy it at the grocery or pet store ) and need to be kept warm with a heating pad under PART of the box so they don't overheat. They sometimes need feedings every 2 hours. They need to be kept in a quiet, darkened, cozy box. CHECK WITH THE NATURE CENTER...or maybe your vet.