What, did you just hear a noise that sounded like baby birds coming from your chimney? Chances are those sounds are coming from baby Chimney Swifts waiting for food. Unfortunately, you can do little about it until the birds are done nesting in your chimney. Why? Because Chimney Swifts are protected under the Migratory Bird Treaty Act.
If you have called a chimney sweep and they have offered to remove the birds, you should know right now that this is illegal and you should be dealing with a different chimney cleaning company. In fact, the proper response from them would be to advise you to not use the chimney and delay the cleaning until the baby birds have left their nest. At this time, the chimney can be cleaned and precautions can be put in place to ensure this does not happen again.
Once the birds are gone, have your chimney inspected and cleaned as soon as possible. At this time, inquire about a chimney cap being installed on the chimney. In addition to the cap, the chimney should be fitted for a protective screen that will further prevent birds, small animals, and leaves from getting into the flue of the chimney. The cap will also help prevent water and other outside elements from getting into the chimney and causing structural damage to the chimney or the chimney liner.
Swifts like to return to previous nesting spaces, so if the problem is not addressed, you will more than likely have the same problem next year. You should know that not taking these precautions can lead to a very dangerous situation for both you and the birds. If the nest has not been cleaned out, it may have become unstable over the course of time and the birds could fall down inside the chimney while nesting. In addition, parasites may have become embedded in the nest, further endangering the birds.