Yellow-legged or Lesser black-backed Gull?- Hastings, UK (1 Viewer)

[Eimajm]

Taken today 01/08/23. It's about time I properly got to grips with these gulls and I need your help. My thoughts are that contrasty head and clear mask and a pretty heavy bill whiteish belly and undertail point to YLG, but I'm really not confident enought yet to call it myself. If this is YLG any thoughts on what LBBG would show at this age that i haven't picked up on, or indeed if this is a LBBG what have I missed!

 

[Alexander Stöhr]

Hello,

interesting bird and excellent picture! Tfs!

A feature according to literature are the darkish shins of juvenile LBBG. I still have to study this in the field for myself (no offence to all authors of fieldguides you know), but your bird seems to have them.
And having looked at (juvenile) YLG last year more closely, my first thought when seeing your picture was: hey, the primaries are really black.
And the head seems rounded, but yes, its a variable feature

Therefore I would opt for a juvenile LBBG. But as always with Gulls ..... Thanks from me too!

 

[Eimajm]

Thanks Alexander, I've not come across shin colour as a diagnostic factor in any gulls before, do you have any links as to where I can look at this please, seems very interesting. I wouldn't get to caught up in differences in colour and shade variations as I have had to process and add contrast which may not reflect the actual 'seen' view. In terms of the tertials what would be your view on the leading edges, they seem to almost reach the greater coverts, but not quite, and there is a reasonable amount of wear to the fringes and some moult starting at the scapulars. I understand YLG would tend to (in the UK anyways) be more advanced than LBBG, should I expect more wear and moulting than this in a YLG?

 

[lou salomon]

the dark shins unfortunately aren't diagnostic, either michahellis and cachinnans can show them in variable amount, but they are more common in LBBG.
this bird gives the impression of a LBBG but to be sure you'd need an open wing (inner primaries - less pale parts in LBBG on inner webs) and open tail (wider black tail band in LBBG, not as tapering towards corners as in YLG).

 

[Eimajm]

the dark shins unfortunately aren't diagnostic, either michahellis and cachinnans can show them in variable amount, but they are more common in LBBG.
this bird gives the impression of a LBBG but to be sure you'd need an open wing (inner primaries - less pale parts in LBBG on inner webs) and open tail (wider black tail band in LBBG, not as tapering towards corners as in YLG).

Thanks Lou for your input, this was the only shot in flight , unfortunately doesn't show the full wing so not sure if useful or not?

 

[vergan]

Thanks Lou for your input, this was the only shot in flight , unfortunately doesn't show the full wing so not sure if useful or not?View attachment 1523915

Useful enough to confirm it as a LBB gull

 

[lou salomon]

Well, actually the flight shot even more makes the identification tricky although now many more important traits are visible:

• tail pattern is very michahellis-like, a narrow band strongly tapering at corners
• Inner primaries look much better for LBBG with the large amount of blackish on inner webs to p1-4.
• there is one moulted scapular which would be quite early for any fuscus but normal for michahellis
• head and underparts are pretty pale for a LBBG, dark mask in a pale head better for michahellis but still possible in LBBG
• dark shins ok for both, rather more common in LBBG
• p5-7 have pale tips which is better for michahellis.

More shots from above in flight might have helped solve this. I'm on the fence with this bird.

 

[Eimajm]

Well, actually the flight shot even more makes the identification tricky although now many more important traits are visible:

• tail pattern is very michahellis-like, a narrow band strongly tapering at corners
• Inner primaries look much better for LBBG with the large amount of blackish on inner webs to p1-4.
• there is one moulted scapular which would be quite early for any fuscus but normal for michahellis
• head and underparts are pretty pale for a LBBG, dark mask in a pale head better for michahellis but still possible in LBBG
• dark shins ok for both, rather more common in LBBG
• p5-7 have pale tips which is better for michahellis.

More shots from above in flight might have helped solve this. I'm on the fence with this bird.

Great stuff, thank you lou and others, a very helpful thread for me even though no definite Id could be made. 👍