Young Squirrel(s) Alone
Very tiny squirrels that have been on the ground overnight should get medical care.
Naked, hairless squirrels and any squirrels in bad weather should be brought to a wildlife rehabilitation center.
Any sound of clicking when it breathes will require medical treatment.
A bloody nose is common, but a wildlife rehabilitator should make sure that the skull isn’t cracked, etc. If the animal appears fine, attempting to reunite the baby with its mother as soon as possible would be the best course of action.
If there are no apparent injuries or lung clicking, place the baby in a box or basket that is tied to the tree it fell from. (Protecting it from ground predation by cats or dogs.) Mothers are most active foraging early in the morning and late in the afternoon.
If found in the morning, leave until the end of the day. If found in the afternoon, leave out until just before dusk.
Bring indoors for the night. Inside the baby should be kept warm and quiet, away from people and pets. A closet is fine! Be sure the box is securely closed, with air holes.
Squirrel With No Hair
Sarcoptic mange, a microscopic mite, is usually the cause of hair loss in squirrels. Many centers do not treat adult squirrels with mange because they will return to their old territory and nest and become re-infected. We can treat young squirrels for mange, but these are rarely seen in the wild. An adult squirrel can survive mange if its immune system is good enough, though if it is really balding badly, euthanasia may be a more humane death. Being eaten to death by bugs is a terrible way to die. Your local wildlife rehabilitation center will be able to determine whether the animal is treatable. There may be a secondary problem that is keeping its immune system suppressed that could be treated.