We have a large barn which has several bird nesting sites, including swifts - although in declining numbers, sadly.
Today I went into the barn and noticed a poor dead swift pressed up against the wall by the window. I was busy and just thought I'll deal with that later, when I noticed it had moved slightly, so wasn't dead!
We lifted it carefully and put it on a low roof, and left it. Went back to check 10 minutes later and it had gone. I did hear a little shriek from above. So fingers crossed!