Those little squirrels that run up your leg are a good example of how difficult it can be to care for young animals. Your first instinct may be to offer it sunflower seeds or hampster food. In fact, these young animals would not have ordinarily have left the nest yet and are therefore still nursing, at least to some extent. What they need is fluids. Finally, a word of caution is warranted.
Young animals can, and do, carry parasites and diseases that can be transmitted to humans.
Depending on the age of the young animal, they may also bite in self-defense. Many wildlife kidnappings occur because we are too quick to judge, or don't have the time to wait - to give the parent and young the opportunity to reconnect. Under Massachusetts law, it is unlawful to have a wild animal in your possession. In addition, migratory birds are protected and regulated by Federal law under the Migratory Bird Act.