To distinguish big gulls (e.g. L. michaellis vs L. argentatus, or their population) the colors on the remiges is very important. The amount of black, the size of the spots, length of the "tongue" and so on.
I would be interested to know whether there are articles or observations about the consistency of this pattern in adults.
For example: if a Larus argentatus has a 3 mm black band on P5 when is 5 years old will it be the same when he is 20?
In other words: does aging matters for the wing pattern?
I hope I made myself clear

Thanks and best,
Pietro