I too spent the afternoon looking at gull photos on the
internet. And I went Ryan one better. I downloaded them
into photoshop, resized them, traced around them and
compared head shapes, forehead slopes, eye position and all
that stuff between Great Black-backed, Slaty-backed, Glaucous
and the Denny photos (Michelle was taking her nap so I couldn't
run the vacuum cleaner).

Structurally, it doesn't look much like a Glaucous or a
Slaty-backed and has much in common with Great Black-backed,
from my perspective. In particular, I found that once the
the bicoloredness of the bill is taken away, the gonys was
more consistant with Great Black-backed of all age classes.

If it is a hybrid, it's not an f1 and I don't even think it's
a recent backcross, so how far back does one have to go before
we can let go of it's past? What large pink-footed gull doesn't
carry a past indiscretion in its DNA?

I say let's either lump 'em all or call it a mostly Greater
Black-backed.

Ryan Shaw noted:
> Did a little surfing, found several immature Great Black-backed Gulls on the
> net with almost the exact same head/bill structure as the Renton bird.
> Take a look at the two immy's on the bottom of this page, even though their
> ages are labeled incorrectly.
>
> http://gullpage.tripod.com/gullspage_en/id12.htm
>
> The adult on the bottom of this page even shows the same head/eye/bill
> structure:
>
> http://www3.sympatico.ca/jeaniron/Gulls04.html
>
> Compare with Denny's shot at:
>
> http://osprey.bardill.net/gallery/album10/P1170055a
>
> cheers
> Ryan Shaw

--
Mike Patterson
Astoria, OR
celata at pacifier.com

Half-a-bee, philosophically must ipso-facto half not-be.
But half the bee, has got to bee Vis-a-vis its entity...
d'you see?
But can a bee be said to be or not to be an entire bee
When half the bee is not a bee due to some ancient injury?
-Monty Python

http://www.pacifier.com/~mpatters/bird/bird.html