From south-bay-birds-bounces+south-bay-birds-archive=[[email protected]] Fri Jan 30 15:28:32 2004 Received: from www.plaidworks.com (localhost [127.0.0.1]) by plaidworks.com (8.12.9/8.12.9) with ESMTP id i0UNO72k017207 for <[[email protected]]>; Fri, 30 Jan 2004 15:24:08 -0800 (PST) Received: from rtjones.nas.nasa.gov (rtjones.nas.nasa.gov [129.99.19.30]) by plaidworks.com (8.12.9/8.12.9) with ESMTP id i0UNNGCR017167 for <[[email protected]]>; Fri, 30 Jan 2004 15:23:17 -0800 (PST) Received: from rtjones.nas.nasa.gov (localhost [127.0.0.1]) by rtjones.nas.nasa.gov (SGI-8.12.5/8.12.5/NAS-6n) with ESMTP id i0UNNF78228039 for <[[email protected]]>; Fri, 30 Jan 2004 15:23:16 -0800 (PST) Received: (from mrogers@localhost) by rtjones.nas.nasa.gov (SGI-8.12.5/8.12.5/Submit) id i0UNNF2i228736 for [[email protected]]; Fri, 30 Jan 2004 15:23:15 -0800 (PST) Date: Fri, 30 Jan 2004 15:23:15 -0800 (PST) From: "Dr. Michael M. Rogers" <[[email protected]]> Message-Id: <[[email protected]]> To: [[email protected]] Subject: [SBB] two RUFFS again X-BeenThere: [[email protected]] X-Mailman-Version: 2.1.2+ Precedence: list List-Id: South Bay Birding List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: south-bay-birds-bounces+south-bay-birds-archive=[[email protected]] Errors-To: south-bay-birds-bounces+south-bay-birds-archive=[[email protected]] All, I had to drop off some paperwork at SFBBO over lunch today 1/30/04, so on the way back I decided to check the pond at State and Spreckles in Alviso. From the car I easily picked out a RUFF, so I stopped and got the scope out - after which the bird disappeared. Scanning around I refound it working in the pickleweed further south on the far shore (railroad tracks side). The bird seemed to have brightly edged upperparts but was distant and often hidden by pickleweed. It foraged actively, moving fast and occasionally flying short distances. A while later I saw a RUFF that seemed duller above, but after watching it for a while and seeing how the appearance changed after the bird flew a short ways I wasn't sure of anything, especially since I could not refind the original bird. Fortunately, both RUFFS eventually came together and, even more fortunately, the helicopter spraying insecticide flushed them to the near side of the pond, where I enjoyed scope-filling views of both birds together with a dowitcher flock. The two birds are indeed quite similar to each other. They are similar in size, overall coloration, leg color, and bill color. They are both notably larger than a dowitcher, especially when they raise their necks. One bird appeared to have darker black flecked feathers on the sides, but this varied greatly depending on how the feathers were positioned. However, it is possible to tell these birds apart with confidence based on the patterning of their tertials and greater coverts. Bird 1 is brighter and more contrasty above, with whiter scapular and mantle feather edges and blacker interiors to these feathers. Most notably, the tertials (which cover the folded wing above the tail) and the nearby greater coverts are bright (almost orange) with black crossbars. Bird 2 is much duller, with uniformly dark-centered tertials and grayer whitish feathers edges; both these feathers and the nearby greater coverts lack any hint of barring. Bird 1 is slightly larger than bird 2, but this is hard to see. On the other hand, it was dominant over bird 2 and did fluff up its head and neck feathers (ruff?) to make itself look really large on a few occasions, something I did not note from bird 2. Both birds got pecked by dowitchers, but bird 1 usually pecked back aggressively. The legs of bird 1 were a yellowish gray that from the rear appeared quite yellowish, but were generally dull. The legs of bird 2 also appeared grayish, but there were hints of flesh/orange tones in places. So where does this leave us with age and sex? Bird 1 is certainly a male and bird 2 would seem to be as well given the close similarity in size. On the other hand, it is smaller and less aggressive. The dull leg color would seem to suggest that these are both first-winter birds, despite the strong differences in the patterning of the tertials. But soft part coloration is variable in many species, and in winter many adults exhibit drabber coloration than during the breeding season, so perhaps this is not completely certain. Sibley paints his juvenile and nonbreeding adult with solid unbarred tertials, whereas both his breeding birds are depicted with barred tertials. The illustrations in the NGS guide generally agree, although the "winter male" does show low-contrast barring on the tertials and adjacent greater coverts. However, the orange base color of the tertials of bird 1 would seem to suggest that they are recently acquired alternate plumage feathers; indeed the contrasty patterns on the scapular and mantle feathers suggest this as well. On the other hand, the patterning of the scapular and mantle feathers of bird 2 was generally similar but just much duller. Does this result from hormonal variation of the birds when the new feathers were acquired? Or are we dealing with different ages/sexes here? (Despite conclusions based on size and leg color.) It will be interesting to continue watching the progress of these birds as they undergo their spring molt. (On the other hand if they are indeed both first-year birds they may keep a fairly "basic" looking plumage throughout their first summer, even if they are males.) It would be really nice to have the companion volume of Peter Pyle's banding guide for shorebirds (he's currently working on all those other species!). In the mean time, please look carefully at the tertials of any RUFFS you see in order to determine which of the above birds is still present. Mike Rogers _______________________________________________ Do not post admin requests to the list. They will be ignored. south-bay-birds mailing list ([[email protected]]) Help/Unsubscribe/Update your Subscription: http://www.plaidworks.com/mailman/options/south-bay-birds/south-bay-birds-archive%40plaidworks.com This email sent to [[email protected]]