WWT Welney

Hi all, I didn't even see the bird behind the swans when I took the picture (just for a change ) There were at least one each male and female Marsh Harriers about, a couple of Buzzards, and a couple of Kestrel, but I'm not confident what this is, any help gratefully received, ta

PS  We were away at a reserve for 4 days....posts will follow...you have been warned