Third-year: Undisclosed Site, Essex - February 2009
Firstly aged as a third-year due to the brown feathering in the tertials and wing coverts and the dark marks on the bill.
Compare the upper-part colour and tone with the surrounding Herring Gulls, darker and bluer than the bird on the left but closer to the bird on the right, though still perhaps with a slightly bluer cast.
The head shape is a little squarer with the peak at the hind crown; the Herring Gull to the right showing a peak almost above the eye.
The bill is rather heavy and blunt tipped whilst the legs are distinctly pale yellow. The eye is pale but not as pale as the Herrings.
Yellow-legged Gull - Larus michahellis
Third-years
 Paglesham Lagoon (3).JPG)
Third-year: Hole Haven Creek, Essex - January 2009
Note the long winged appearance; square looking head; deep blunt tipped bill and dark blue-grey upper-parts.
Third-year: Hole Haven Creek, Essex - January 2009
Compare with the near-adult Herring Gull at the front.
The upper-parts are darker blue-grey; the primaries project further; the head is clean unmarked white and hefty bill with deep Gonys expansion.
As can be seen it was a rather large bird.
Third-year: Paglesham Lagoon, Essex - December 2006
The square head with peak at the hind crown is obvious here as is the deep hefty looking bill whilst the upper-parts are clearly a few shades darker than the background Herring Gull.
Third-year: Undisclosed Site, Essex - 29th August 2009
This summer bird is a little strange in that although it has completely grey upper-parts that would be expected of a third-year the primaries large mirrors and white tips, save for the finest of white tips to P10. The primaries also look rather brown.
In addition the bill has a broad black band, though the edges of the red Gonys spot are visible. The bill though is typical Yellow-legged Gull, hefty, bulbous and blunt tipped.
This could be a retarded third-year, retaining older second-year primaries, or a very advanced second-year; there's not much obvious visible wear and tear to the primaries.
Third-year: Undisclosed Site, Essex - 29th August 2009
The same bird as in the previous image: here there is an obvious white mirror visible to the under-side of P10 which is more supportive of a third-year though again the change of angle has not revealed any white primary tips.
Note the graellsii Lesser Black-backed Gull sat down at the back and compare upper-part tones.