The plumage of this indivisual is somewhere between 3rd and 4th calendary year. I suggest the individual to be considered as a retarded (in appearence) 4th calendary year but in my opinion it's tricky to tell for sure why its' not a 3rd. The P10 mirror exists but it's not very consistent, the tail, secondary and covert pattern is also somewhere inbetween both plumages.
29 June 2009
26 June 2009
22 June 2009
2nd c. y. Audouin's gull (L. audouinii), 07-06-09. Accordintg to Pep Arcos comments, the bird could be a more retarded individual of 3rd c.y.
10 June 2009