Monday 13 December 2010

Herring Gull (Larus argentatus) with leucisme

This leucistic Herring Gull with primary pattern and upperparts ghosting normal colorations was seen in the central section of Aarhus Harbour on December 12, 2010. All photos were taken by Peter Nielsen.

In some of the photos one can get impression of some Kumlien's Gull impressions due to the round head with darker eye and rather long primary projection, but the overall jizz is somewhat of a flat backed, slender gull with large head, rather strong bill, reduced tertial step, reduced white tertial and scapular crescent and without a short and plump body.

There are two coverts on the left side which looks wet, but in fact show a degree of normal pigmentation and thus appear darker then the remaining upperparts.

New photos of the same individual are here including the standing bird and stretched wing.







3 comments:

Morten Helberg said...

Hei Kent

Dette må jo være en hvidvinget måge (grønlandsmåke på norsk) og ikke ei sølvmåge? Forttrinnsvis av formen kumlieni da den har mørkegrå vingespisser. Lys grå rygg, rundt hode og håndsvingfjærprojeksjon passer jo helt fint etter min smak :-)

MVH

Morten Helberg

Kent Olsen said...

Morten,

Thanks for your comment. But to me this is just a leucistic Herring Gull. I fully acknowledge that one can get a small gull impression due to the round head and darker eye, but to me the jizz is somewhat of a flat backed, slender gull with large head, rather strong bill and reduced tertial step; thus it lacks the short and plump body together with other classic glaucoides-traits.

As fare I can tell there are two coverts on the left side which looks wet, but in fact show a degree of normal pigmentation and thus appear darker then the remaining upperparts.

Cheers

Kent

JanJ said...

More likely a Herring on structure and bill dimensions, especially compared to glaucoideskumlieni.
Among several differences, another feature to support this is the blackish underside to p10, which is not good for kumlieni.

Cheers

JanJ