Black-headed Gull, Larus ridibundus
Below, there were up to fifty of these handsome gulls in Clissold Park during two weeks in late December 2009 that we spent just a block away. The ponds froze over during this cold spell, providing some nice gull-on-ice views.
Above, four years later, I was finally able to photograph a Black-headed Gull in breeding plumage, this one flying over the river in Stratford-upon-Avon. The name is misleading because the birds in summer have dark brown rather than black heads, as shown here.