I'm confused...wasn't that the egg that MAK found on the street. Or maybe I missed something...
Forgot about that - I'm going to blame it on the heat!

I believe you are right...
Does anyone else see a landing falcon with wings raised in the stain on the south side of the nestbox? (Upper right corner.) Or is it my eyesight playing tricks on me?

At first, when I read your post, I thought, "Whaaa?" But then Looked at he wall of the nest box. Yes, I do see what you are seeing. Maybe it's just wishful thinking. It looks like an in-coming falcon with wings up!
Maybe we have been watching too long? LOL!