Date: 1/30/18 2:15 am From: Robert O'Brien <baro...> Subject: [obol] Armchair Gulling--Sauvie Is. Pellet Plant 1993 redux #2d
If you work with these guys you can get them to pose. (I promised them a hot dog each since a constant diet of saltine cracker packages (the PP's main fare) didn't seem good, what with breeding coming up and all.)
This pair reinforces Lars' earlier Western Gull comments. This is a much larger Slaty-backed than the previous ones with a proportionately longer bill, still quite slender but it does have a slight bulge in the lower mandible at the end. It's sorta off yellow compared to the Western Gull's bright orange/yellow bill. This SBGU may be a little larger than the Western but I couldn't convince the others to get out of the way. The dark feathering around the eye is getting fainter and you can get a hint of the large, off-white eye, compared to the Western Gull's beady little eye.
You can see that the Slaty-back has a darker, slatier(!) back than the Western Gull, but this can be quite variable along with size, as the next installment will show.
The 'jizz' of these two birds is quite different, but that would maybe be hard to pick up without a direct comparison. I'm a big fan of jizz but you don't hear that word very often these days. I've (mis)identified lots of birds just by using jizz alone!
Now, I'm also a big fan of making a gull ID chart just for adults if you're just starting out. I did it myself, and maybe should do it again. But as others have said, there's no way of getting around time in the field. So beware of naming this Slaty-back as a Ring-billed Gull. (Hee hee, I know you'd never do that).
But the ringed bill does illustrate that this bird is a different individual than the SBGUs in previous posts. The bill may indicate this bird is just finishing it's 3rd year and going to be a full adult at 4 years old.