There was an excellent picture of a juvenile gray squirrel in the Wednesday, 10/3/12 issue of the Times Gazette. The photo was taken by Brian Moseley.
The caption mentioned that the squirrel had no fear of humans and tried to jump on Brian's shoes as he was taking the picture. This falls right in line with some of the points I have been making in my recent blogs.
Juvenile squirrels under normal circumstances are not "friendly". They are just as happy to bite you as their elders are. By the way, squirrels have teeth that are more than 1/2" long. I have been bitten several times where the teeth sank all the way to the bone . I feel confident in stating that this young squirrel was in distress.
This is a classic case of a starving squirrel. In all likelihood, its mother is dead, and it has not yet learned how to secure food for itself. Young squirrels do not have good visual skills. When they are very hungry they will run to anything that moves in the hope that food will be supplied. When food is offered, they become very aggressive because they are so hungry.
In cases like these a rescue is appropriate. A person would need an animal crate, or a very sturdy cardboard box. Always use gloves! Wild animals bite for different reasons, and starvation is one of them! A temporary diet to offer would consist of shelled, unsalted nuts, apples, wheat bread, and water. The animal would need to go to a licensed wildlife rehabilitator to give it the best chance for survival in the wild.
Just an FYI, at the Walden's Puddle facility, all of the staff who worked directly with animals received a series of pre-rabies vaccinations. Even so, we took great pains - no pun intended - to avoid being bitten.