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Ring-billed gull - Bulgaria (1 Viewer)

Yordan_13

Active member
Hello! I posted this gull before and received mainly suggestions for delawarensis, but also some for canus. Recently I looked it up again and saw some signs that could exclude canus and werent mentioned before or I didn`t know about. Some of the characteristics pointing towards RBG were stronger bill with curved upper mandible, pink base with black tip, also square head shape, the head and neck streaking with lunary-shaped apical part of breast feathers. The features that are strongly pointing RBG, that I didn`t notice before, are the strongly worn tail and wing juvenile feathers, which are much fresher in CG, also the replacement of some median and lesser coverts along with some tertials which is said in papers never to occure in CG at this time of the year. Also on the coverts, on the both sides, I think that still can be seen some atypical barred feathers for canus and more fitting for ring-billed.

Are these features enough to exclude canus from the competition?
Fron Bulgaria 14 Jan 2017
 

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HH75

Well-known member
Ireland
Hi Yordan,
For me, this is a 1st-winter Ring-billed Gull, an amazing Bulgarian record, especially these days with the decline in European records. You already gave the reasons why this differs from a Common Gull, regardless of taxon: while Kamchatka Gull can resemble Ring-billed at this age in some respects, that is still much closer to nominate Common Gull, and wouldn't have the second generation coverts scattered in, chevron markings on the flanks or slight brownish subterminal markings on some of the second generation scapulars.
Regards,
Harry
 

smiths

Well-known member
Sorry to ruin the fiesta, but I feel pretty sure that this is a Common Gull.
Variation in this species is not to be underestimated, especially when you take into account not just ssp. canus but also heinei.

  • The bill shape of this bird, with a long, pointed tip, fits Common much better than Ring-billed Gull. A bright pink bill base is shown by some 1w canus and is entirely normal in 1w heinei. I would assess the bill pattern of this bird as clearly indicating the former: the bill tip is not as deep black as in Ring-billed, it fades to slightly greyer towards the nostril, and there is a black line running along the cutting edge, unlike Ring-billed. In that species, the bill pattern is more clear-cut and bicoloured, like Glaucous Gull.
  • The tail pattern is typical of Common Gull. Ring-billed does not show this combination of solid dark wedges along the shafts + clean white outer web to outermost tail feather.
  • The pattern of the remaining juvenile lesser and median coverts, with rounded brown wash and simple dark shaft streak, is typical of Common Gull and (very) unusual for Ring-billed, even in worn plumage.
Some 1w Common Gulls do moult a number of wing coverts and/or tertials; this may even be the case in early December of the 1st calendar year already.
Brown subterminal markings on new scapulars are quite frequent in this species.
Also, distinct V-shaped marks on breast/flank area are not that unusual, both in heinei (two examples from Georgia attached) as in canus (http://gull-research.org/canus/pages/commongull42.html ; Common Gull Macaulay Library ML39540041).
 

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HH75

Well-known member
Ireland
Sorry to ruin the fiesta, but I feel pretty sure that this is a Common Gull.
Variation in this species is not to be underestimated, especially when you take into account not just ssp. canus but also heinei.

  • The bill shape of this bird, with a long, pointed tip, fits Common much better than Ring-billed Gull. A bright pink bill base is shown by some 1w canus and is entirely normal in 1w heinei. I would assess the bill pattern of this bird as clearly indicating the former: the bill tip is not as deep black as in Ring-billed, it fades to slightly greyer towards the nostril, and there is a black line running along the cutting edge, unlike Ring-billed. In that species, the bill pattern is more clear-cut and bicoloured, like Glaucous Gull.
  • The tail pattern is typical of Common Gull. Ring-billed does not show this combination of solid dark wedges along the shafts + clean white outer web to outermost tail feather.
  • The pattern of the remaining juvenile lesser and median coverts, with rounded brown wash and simple dark shaft streak, is typical of Common Gull and (very) unusual for Ring-billed, even in worn plumage.
Some 1w Common Gulls do moult a number of wing coverts and/or tertials; this may even be the case in early December of the 1st calendar year already.
Brown subterminal markings on new scapulars are quite frequent in this species.
Also, distinct V-shaped marks on breast/flank area are not that unusual, both in heinei (two examples from Georgia attached) as in canus (http://gull-research.org/canus/pages/commongull42.html ; Common Gull Macaulay Library ML39540041).
Hi Peter,
Many thanks for your comprehensive analysis. While I have no experience brachyrhynchus or kamtschatschensis, and effectively none of heinei (a handful on range at distance in Kazakhstan and a very distant 1st cycle in Oman), and I don't even see the sheer number of individual canus per annum that you would, I must confess that I've never seen a Common Gull with multiple moulted second generation coverts like this, and it's a real eye-opener. In your extensive experience, how regular is this?

By the way, despite the impression I may have given when I listed the dark markings on some second generation scapulars as being in favour of Ring-billed Gull, I meant that more as a supporting feature, as I've definitely seen plenty of 1st cycle canus locally with some scattered dark markings, especially as I've been photographing birds at close range this winter. But the extensive post-juvenile moult is certainly a new one on me, every day's a schoolday!

Regards,
Harry
 

smiths

Well-known member
I must confess that I've never seen a Common Gull with multiple moulted second generation coverts like this, and it's a real eye-opener. In your extensive experience, how regular is this?
I have not quantified this myself; I think it is quite rare, though I guess it may vary according to the climate in the wintering range.
Also, no doubt that the more you go looking for such birds, the more you'll find them.
I have attached an example from my series of Common Gull photos, although that bird was photographed somewhat later in the season, i.e. in mid March (in Belgium).

There was a discussion on this topic in the Western Palearctic Gulls group on Facebook recently.
In a series of 175 first-cycle canus observed in London on 25 Dec 2021, Amar Ayyash counted 6 or 7 with a number of replaced wing coverts.
Among 130 photos of 1c canus, David Darrell-Lambert found one with replaced coverts, also photographed in London, on 19 Jan 2019.
In addition, Sylvain Reyt posted photos of one bird with replaced coverts, from France in early December.
Because they are so instructive, I have attached their photos here, with the photographers' names in the file names. I hope that is alright!
 

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