If you find an injured bird and want to ensure its safety, there are some steps you can take.
Avoid stressing the bird further by eliminating any distractions. If you have other animals, or children keep them away so as not to harm the bird.
Contact a licensed wildlife rehabilitation professional in your area. You can find the phone number of people who are licensed by the state and federal government to care for injured wild birds from your state game or wildlife agency. You can also call your local animal shelter to find rehab centers; some have their own on-site rehab centers, separate from domestic animals. Wild birds are protected by federal laws. You can also try calling a veterinary hospital that treats birds, and they may be able to direct you to a rehabilitation site.
Find a cardboard box or other container to hold the bird. Be sure the container is bird-safe (won't entangle the bird's wings or feet, isn't air tight, NO wire cages that will break the bird's feathers). The box should be large enough that the bird can move and turn around in, but not too large that it can flap and fly and cause further harm to himself. Poke holes into the sides of the box as well as on the top so the bird can easily breathe. Do this before placing the bird in the box.
Approach the bird slowly and drop a towel gently over top of it. Have patience. If you cannot come close enough to the bird to do this, do not chase it. Use a towel that will not unravel. The birds nails can easily get caught in towels that are terry cloth or have loops in the fiber.
Scoop up the bird in the towel and very gently place it into the box, towel and all. Secure the box with tape, being sure that there is enough air circulation for the bird to breathe. Keep the box in a dark, warm area where there are no loud noises. You can keep a heating pad on low under one half of the box. If you have to take the bird in yourself to the rehab center, do not have a radio on in your vehicle- noises will frighten the bird.
Do not attempt to feed the bird or perform any first aid. Birds are very easily stressed by handling and need an experienced veterinarian to care for them.
Deliver the bird to a licensed wildlife rehabilitation professional or a veterinarian who is willing to accept the bird. It is illegal (in the USA) for unlicensed individuals to possess any wild bird for any reason beyond overnight care before transporting to a rehabilitation site. Birds have diverse requirements for diet, care and wild birds do not adapt well to captivity.
Ask the rehabilitation expert if you can release the bird if he is able to get well again. Often birds should be released near where they were found. That is the best reward for the kindness of rescuing an injured bird!
The Migratory Bird Protection Act is a federal law protecting all native wild birds in the U.S. It is a federal and state offense to keep a wild bird without a license.