[2cy vs. AD] Black-headed gull (Larus ridibundus)

It's quite easy to aged 2cy Black-headed gull (Larus ridibundus). This post should help ringers to do it. There are two main features to differ 2cy and Ad:

2cy:- alula dirty dark, with dark outer
- bill and legs orange or dark orange

Ad:- alula clear white/silver
- bill and legs red

fot. Marcin Sowa - 2cy alula, dirty dark

fot. Marcin Sowa - legs of 2cy

fot. Marcin Sowa - feet of 2cy

fot. Marcin Sowa - bill and legs of 2cy

fot. Marcin Sowa - bill and legs of ad

fot. Marcin Sowa - ad alula, clear white