At this time of year, it’s common to find injured or abandoned birds. At our vet clinic just now, somebody arrives every day holding a small bird, and asking us to help them. People often do the wrong thing, and the birds die as a result. I’ve recorded a podcast explaining the best steps to take, but essentially, there is one simple thing to do.
Visit an excellent website – IrishWildlifeMatters – where you can click on a flow chart, answering questions about the bird you’ve found, and you’ll be guided to the right thing to do for the creature in your care.
Please note that I am unable to answer veterinary questions in comments. If you have questions or concerns about your pet's health it is always better to contact your vet.