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Variations in Herring Gull (Larus argentatus vegae) - Japan (1 Viewer)

jmorlan

Hmmm. That's funny
Opus Editor
United States
Presumed Herring Gull (Larus argentatus vegae) 9 February 2019. Choshi--Choshi Port, Chiba Prefecture, Japan.

Here are two first cycle presumed Vega Gulls which stand out as different among my photos. The first is strikingly more contrasting but pattern resembles typical birds although with less dark on the greater coverts and mantle. The second is a dark extreme with the mantle feathers almost completely filled in and more extensive dark markings on its wing coverts. Structurally both are similar. Are these within normal range for first cycle Vega?
 

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Presumed Herring Gull (Larus argentatus vegae) 9 February 2019. Choshi--Choshi Port, Chiba Prefecture, Japan.

Here are two first cycle presumed Vega Gulls which stand out as different among my photos. The first is strikingly more contrasting but pattern resembles typical birds although with less dark on the greater coverts and mantle. The second is a dark extreme with the mantle feathers almost completely filled in and more extensive dark markings on its wing coverts. Structurally both are similar. Are these within normal range for first cycle Vega?

IOC9.1 gives L. vega as full species, Vega Gull, the nominate and mongolicus as subspecies, citing Collinson et al 2008.

However, Liebers-Helbig et al 2010 suggest L. smithsonianus vegae as 'Vega Gull', as a subspecies of American Herring Gull, or, to emphasise two lines of ancestry, L. smithsonianus/vegae vegae form the likelier options. The latter approach would make 'Mongolian Gull L. s./mongolicus mongolicus...
MJB
References
Collinson, JM, DT Parkin, AG Knox, G Sangster and L Svensson. 2008.
Species boundaries in the Herring and Lesser Black-backed Gull complex. Brit. Birds 101(7): 340-363.
Liebers-Helbig, D, V Sternkopf, AJ Helbig and P de Knijff. 2010. The Herring Gull Complex (Larus argentatus - fuscus - cachinnans) as a Model Group for Recent Holarctic Vertebrate Radiations. In: M. Glaubrecht (Ed). 2010. Evolution in Action. Springer-Verlag, Berlin & Heidelberg, Germany. (doi 10.1007/978-3-642-12425-9_17
 
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Yes, I appreciate the taxonomic fuzziness. But as for the birds themselves, how do I tell the dark Vega gulls (presumably with delayed first cycle molts and retained juvenile plumage into February) from first cycle Taimyr (Heuglin's?) Gulls?

Thanks in advance.
 
Yes, I appreciate the taxonomic fuzziness. But as for the birds themselves, how do I tell the dark Vega gulls (presumably with delayed first cycle molts and retained juvenile plumage into February) from first cycle Taimyr (Heuglin's?) Gulls?

Thanks in advance.

I can't help on gulls myself. But you might like to try looking at the gull-related posts on Neil Davidson's Japan blog. He's a serious gull specialist himself.

And if you have a Facebook account, you could join Kantori, a Japanese bird fanatic group who are mostly based around Tokyo and therefore have informatiion about Chiba; I think there are gull specialists there, too.
 
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