A Hobby chased Swifts around the church shortly before dusk. It was nearly dark and was very reminiscent of a Bat Falcon! One of 'my' Swifts had already roosted but I think the other was still involved in the melee. The Hobby failed anyway.
Also, about 300-400 Lesser Black-backed Gulls as well as a few Black-headed Gulls flew towards Cambridge. I'm guessing they may be roosting at Milton Country Park.
