January 3rd 2007. Rochester Waste Water Treatment Plant, NH. Slaty-backed Gull. Larus schistisagus. Adult winter. This large, dark-mantled, adult gull was discovered by Mike Harvey at Rochester Waste Water Treat Plant on January 2nd. Thanks to Mike's alert, several birders including Steve Mirick managed to get to Rochester before the plant closed at 3pm. It was generally agreed that the bird showed at least some characteristics consistent with an identification of an adult Slaty-backed Gull. I made the trek out to Rochester from Amherst the following day. After over five hours of gull watching, a handful of us eventually located the subject gull with just 20 minutes to go before the plant closed for the day. Shortly afterwards a marauding Bald Eagle flushed all the gulls, and we lost contact with the Slaty-backed. The result is the rather limited image selection below. Update January 7th: I'm now beginning to receive comments on the identification of this bird. So far, all of the comments that I've received personally have been of a positive nature. From Hector Galbraith, Vermont on 01/05/07; “James, I have seen two adult SBGU over the last few years in Colorado and on the West coast. This one looks like a pretty good fit with the pink legs, fairly heavy-tipped bill, slate-grey mantle, relatively short wings, and extensive area of white on the tertials and secondaries. The only feature that I have not seen a good photo of yet is the "string of pearls" on the primaries. Did you get a look at that?” After this I referred Hector to the link with Mike Harvey’s image selection. From Alvaro Jaramillo, California on 01/06/07: "James I looked at the various photos of the gull you guys have and I would have no hesitation in calling that a Slaty-backed Gull. Super. I think we are seeing the new Lesser Black-backed Gull, we are getting colonized from Asia this time! Cheers Alvaro" Alvaro Jaramillo Half Moon Bay , California Field Guides - Birding Tours Worldwide www.fieldguides.com Part of a follow-up email from Alvaro on the iris color of the Rochester bird; “ If you look at the Ujiharas site many of their birds do not have the typical yellow eyes, and there are a few they single out as having dark eyes without making a big fuss about this. My guess is that 90% or more are yellow eyed, and most of the rest have some dark speckling in the eyes”. Here's a link to Alvaro's latest Slaty-backed find at Half Moon Bay, CA on January 5th, 2007. The same page will also take you through to a number of Alvaro's carefully documented Slaty-backed Gulls on the California coast. From Osao & Michiaki Ujihara, Japan on 01/06/07: "Hello James P. Smith Thank you for your e-mail. We agree with your thought about the gull. All features including its wing-pattern seem to indicate this is a Slaty-backed Gull. The short P10 in Jan seems to be the only feature that is slightly different from the majority of Slaty-backed Gull wintering in Japan. But we suspect northern individuals (easier to wander to North America) can show late molts like this. And we feel the deep pink legs also can be a good sign to exclude SmithXGBBG or SmithXLBBG. Osao & Michiaki Ujihara" After a follow-up email on the upperparts tone of this bird; “Hello As long as we see the photos, the upperparts tone of your bird is within the normal range of Slaty-backed Gull. Ujihara.” Further images of the Rochester Gull from January 2nd have been posted by: Mike Harvey & Steve Mirick (Mike Harvey's image selection also includes the third-winter Slaty-backed Gull discovered by Jeremiah Trimble et al at Rochester on January 18th, 2007.) More images of the adult Slaty-backed Gull from a second visit on January 10th. An impressive selection of Slaty-backed Gull images can be seen here on the Japanese Gull Site. They include a interesting range of upperpart tones shown by adults photographed in winter in Japan. Images taken using Canon Powershot A540 through Swarovski HD Telescope. |
 More difficult than expected to pick out from the mass of gulls coming, going and eventually resting on the ice at Rochester WWTP.   Not only impressively rosy-pink legs, but I was also struck by how thick-legged this beast appeared in the field. The knees and tarsus look especially thick here compared to the surrounding American Herring Gulls.     A reasonable view of the iris which looked yellowish-brown or amber in the afternoon light.   The result of a fly-over Bald Eagle at Rochester. Just when I thought that I'd missed out on an open wing shot, I looked at this image more carefully and found the underwing of the Slaty-backed Gull. Look for the 'three-toned' (dark blackish-gray, slate gray and white) underwing in the mid-upper left of the shot. Note the contrast between the white underwing coverts and slate gray remiges with a broad white trailing edge.  Although the upperwing of an American Herring Gull obscures part of the underwing of the SBGU, it's possible to see white 'pearls' on P-8, P-7, and P-6. The white trailing edge contrasts neatly with the slate gray remiges. |