Black-headed Gull - Larus ridibundus
Adults
Black-headed Gull - Adult summer, Undisclosed Site, Essex 11th April 2009
Note the brown hood, not black as in Mediterranean Gull, a wrongly descriptive bird name if ever there was one. The hood extends from the throat, behind the ear coverts and up onto the crown; it does not encompass the whole head as in Mediterranean Gull. The white eye crescents are narrow and do not meet in front of the eye.
The bill is slender and all dark/deep red and the legs are dark red.
The upper-parts are plain pale grey.
The primaries extend well beyond the tips of the tertials and black with white outer edges and small white tips, becoming increasingly larger on P7 and P6. The outermost edge of P10 is black forming a black leading edge to the white window.
The overall build is slender, rather attenuated and with a small head.
Black-headed Gull - Adult summer, unkown, Essex March 2007
Note the same features as detailed in the previous image.
Black-headed Gull - Adult summer, Paglesham Lagoon, Essex 30th June 2008
Note the brown, not black hood, narrow white eye crescents which do not meet in front of the eye, slender all dark red bill and plain grey upper-parts with not contrasting pale trailing edge.
On the spreadwing:
White leading edge formed by mostly white outer primaries; black trailing edge to the primaries and grey inner primaries.
Black-headed Gull - Adult summer, Paglesham Lagoon, Essex 30th June 2008
The odd wing shape is due to missing inner primaries.
The underside of the primaries are dusky with the white of the outer webs greatly reduced; On Boneparte's Gull, all ages, the inner primaries are silvery white.
Black-headed Gull - Adult summer, Undisclosed Site, Essex 5th April 2010
An unusual bird that exhibits brighter than normal bill colouration, bright orange, and bolder and broader white 'eye-lids' which meet at the rear of the eye.
Note the legs are deep red but with orange knees and heels whilst the grey upper-parts are slightly paler than on a typical Black-headed Gull.
Below compared with a normal adult summer Black-headed Gull.