Chimney Swifts are birds that tend to inhabit chimneys between April and August. Although we do extractions of animals, Chimney Swifts are a protected species and once settled into your chimney, it is illegal to remove them. Some unscrupulous chimney companies will still do it, but it is against the law.
We tell our customers, that once they have flown away, usually around the end of August or beginning of September, we can remove the nest, sweep the chimney, and install a chimney cap. The only reason they got into your chimney in the first place, is because there was no cap.
Below are pictures of Chimney Swifts. They resemble Barn Swallows.