A worldwide community photographing and learning about wildlife
Aythya fuligula
In a man-made pond.
That's quite a bit of white on the bill for pure Tufted. How about Tufted x Ring-necked Duck hybrid?
http://www.flickr.com/groups/hybridbirds...
I think this is a tufted duck as suggested by Ava. Amongst others the greater scaup has a head with a green sheen.