A squirrel who is nearly full-sized, has a full and fluffy tail and can run, jump and climb is independent. However, if a juvenile squirrel continuously approaches and follows people, then mom is probably gone. In this case, you should contact a licensed wildlife rehabilitator because the baby is very hungry and needs care.
There are a few cases where you might need to intervene:
A baby squirrel falls from a nest
A nest falls from a tree
A felled tree contains an intact nest
If the baby and/or their nest fell from the tree today, give the mother squirrel a chance to reclaim the young and relocate them to a new nest. If the baby is uninjured, leave it where it is, leave the area, keep people and pets away, and monitor it from a safe distance.
If it’s chilly outside or the baby isn’t fully furred, place it in a shoebox or other small container with something warm underneath (like a hot water bottle). Be sure to place something soft (old towel, T shirt) between the baby and the heating device, or it could overheat. Do not cover it with anything or the mother might not be able to find it.
If the babies are not retrieved by dusk, take these steps:
Wearing thick gloves, gather the squirrel(s) and place them inside a thick, soft cloth, such as a cloth diaper or fleece scarf or hat.
Place one of the following items beneath the cloth:
a chemical hand warmer inside a sock,
a hot water bottle (replace the hot water every 30 minutes) or
a heating pad set on the lowest setting. (If the heating pad has no cover, put it inside two pillow cases so the babies don’t overheat.)