When you come upon an injured bird or a chick on the ground that appears to be orphaned, your first instinct is to help. But it’s always best to stop and think. In many cases, the best action is to do nothing.
However, if you encounter a bird that is obviously injured – or if it will be in danger if it remains where it is – do your best to take it to a safe place. Remove it to a cool, safe place, if possible. Birds go into shock very easily, and anything you can do to keep that from happening will greatly improve the bird’s chance of survival. Don’t try to feed the bird or make it drink. If a bird has just hit a window, it may simply need time to regain its senses. If it has obvious injuries (such as bleeding or a broken wing), you should try to contact a wildlife rehabilitation agency. Los Angeles Audubon has a great list of contacts in the Los Angeles area.
If you have found a chick on the ground, it is almost always best to leave it where it is. When many young birds first fledge and leave the nest, they may still have a little down with short tail and wing feathers. Fledglings often also have weak flight muscles and may be fed for a few days by their parents outside of the nest. This is a vulnerable time for young birds, as they are easy prey for roaming cats and other predators. It is important to keep fledglings safe and to allow the parents to continue feeding them. If the bird has fallen out of the nest prematurely, or if a tree was cut down and a nest of young is found, a rehabber may be needed.