Larus Argentatus ~ scarce atypical tail pattern ~ 1st. W ~ Dungeness, Kent - 21.09.13

Larus Argentatus

Scandinavian Herring Gull

This particular 1st. Winter individual shows a scarce atypical tail pattern

White band through the normal broad tail band

A pale looking bird, contrasting with the dark alula, outer greater coverts, outer primaries, secondaries, tertials and tail band 

* Note the very faint pale band running through all secondaries even the primaries ...

* DM suggests its a possible dietary deficiency or other trauma during feather growth which could affect the pigment resulting in the tail band.

Maybe from previous generations past, there was mixed parentage ie: hyperboreus or marinus that possibly bred with argentatus which could throw off genetically these tail patterns. 

There's a  few images of this trait to be found on the web but it seems either little is known or just a lack of info, as yet i've only seen images of this tail pattern on argentatus or putative birds but not on argenteus.