EDIT 5/26/2016: If you found this post because you have a baby bird and are wondering what to do with it, please see this post instead; it will be more useful.
Being a fledgling—a chick that has left the nest—is awkward.
Fledglings are at one of the most dangerous time in their lives, facing an average mortality rate of 42% over just a week or two. Most of that mortality happens early, just after the little guys have left the nest. New fledglings have almost no skills: they can’t feed themselves, can’t fly well (or, in many cases, at all) and can’t do anything to defend themselves if something terrifying like a weasel, snake, crow, or even chipmunk decides to eat them.