10 October 2016

Possible 1st Cycle Herring x Lesser Black-backed Gull

I'll begin this post by reiterating - as I always do - that I'd much rather leave confusing young gulls unidentified than assign a hybrid label to them. There is no sense in jumping to conclusions when there are no data to support them.

With that said, here's a bird I first thought may be a 1st cycle Lesser, then decided it was okay for a 1st cycle Herring, and then started scratching my head the longer I looked at it.

Structurally, the rear looks very little like an American Herring and much more like a Lesser. The sparsely marked vent area is also unusual.  
The, longer, solid outer median and lesser coverts also resemble Lesser Black-backed, more than American Herring.
"This is NOT a pure American Herring" were my thoughts after seeing the undertail.
The white vent is not something I've encountered with juvenile American Herrings. But now see the open wing...
The uppertail contrasts greatly with the rest of the body, but most disturbing is the strong contrast to the pale inner primaries (only seen well in brighter lighting).
In this slightly underexposed image, it looks long-winged, shows less of an inner primary window, and the tail almost looks like it was trying to go for a banded look but failed miserably. 
If this is an American Herring Gull or Lesser Black-backed Gull, then I have to admit that I don't yet know these species well. It sure doesn't feel right for either taxon. On the other hand, it does look intermediate in many ways. Another one for the mystery file.