A Yellow-legged Gull transitioning from its 2nd to 3rd calendar years visited Olton Mere, West Midlands, regularly between mid-November 2015 and mid-March 2016, while what was assumed to be the same individual reappeared in July 2016 (and perhaps the same again January 2017).

Plate 1. 2cy (2W) Yellow-legged Gull, November 2015, West Midlands

Plate 2. 3cy (2W) Yellow-legged Gull, January 2016, West Midlands

In two images above note uniformly dark grey 'saddle' and grey already emerging in median and greater coverts. The inner greater coverts are strongly barred,
contrasting with the relatively plain outer greater coverts. Head-shape varying with posture.

Plate 3. 2cy (2W) Yellow-legged Gull, November 2015, West Midlands

Plate 4. 3cy (2W) Yellow-legged Gull, January 2016, West Midlands

With a combination of uniform, slate-grey 'saddle', rather dark coverts and white base to tail, 2W YLG has superficial resemblance to an over-sized 1W Common Gull,
both at rest and in flight (but note new adult-like inner primaries).

Plate 5. 2cy (2W) Yellow-legged Gull, January 2016, West Midlands.

Head-shape is dependent on posture but often with characteristically angular profile (long flat crown and rather vertical nape).
Compare head and bill shapes and mantle colour with adult LBB to rear.

Plate 6. 3cy (2W) Yellow-legged Gull, January 2016, West Midlands.

Plate 7. 3cy (2W) Yellow-legged Gull, January 2016, West Midlands.

Black tail band contrasts strongly with clean white base to tail.

Plate 8. 3cy (2W) Yellow-legged Gull, February 2016, West Midlands.

Clean, slate grey mantle and rather white-headed appearance characteristic of michahellis at this age. At close range, diffuse and subdued streaking visible on cheeks, nape and sides of throat.
Bill with pale yellow base but extensively dark tip. Iris becoming pale.