From south-bay-birds-bounces+south-bay-birds-archive=[[email protected]] Fri Jun 13 13:14:37 2003 Received: from www.plaidworks.com (localhost [127.0.0.1]) by plaidworks.com (8.12.9/8.12.9) with ESMTP id h5DKBea8010259 for <[[email protected]]>; Fri, 13 Jun 2003 13:11:41 -0700 (PDT) Received: from rwcrmhc13.attbi.com (rwcrmhc53.attbi.com [204.127.198.39] (may be forged)) by plaidworks.com (8.12.9/8.12.9) with ESMTP id h5DKAvfF010215 for <[[email protected]]>; Fri, 13 Jun 2003 13:10:58 -0700 (PDT) Received: from computer.attbi.com (12-234-255-153.client.attbi.com[12.234.255.153](misconfigured sender)) by attbi.com (rwcrmhc13) with SMTP id <2003061320105501500da7dpe>; Fri, 13 Jun 2003 20:10:55 +0000 Message-Id: <[[email protected]].> X-Sender: [[email protected]]. X-Mailer: QUALCOMM Windows Eudora Version 5.1 Date: Fri, 13 Jun 2003 11:01:18 -0700 To: Al Eisner <[[email protected]]>, [[email protected]] From: Alvaro Jaramillo <[[email protected]]> Subject: Re: [SBB] County birding In-Reply-To: <[[email protected]]> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed X-Content-Filtered-By: Mailman/MimeDel 2.1.2+ Cc: 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]] At 10:01 AM 6/13/2003 -0700, Al Eisner wrote: >Bob Reiling wrote: > > > Our (Frank Vanslager and my) first destination this morning was the > mouth of > > Stevens Creek. Lots of BLACK-BELLIED PLOVERS (mostly juveniles), several > > CALIFORNIA GULLS, a few WESTERN GULLS, several FORSTER'S TERNS, two > LONG-BILLED > > CURLEWS and a BONAPARTE'S GULL. Two different large stick nests in > power towers > > along the creek had COMMON RAVENS in/on them. Four LESSER SCAUP (three > > males) were in Salt Pond A2E. There was lots of water in Crittenden > Marsh but very > > little else of interest (ditto the latter for Stevens Creek Mitigation > Pond). > > A stop at the Palo Alto Yacht Harbor, the Duck Pond, a walk out to > "Clapper > > Creek" and a short drive to the harbor entrance failed to produce any > notable > > birds. Our last stop at Charleston Slough, Adobe Creek etc. produced four > > young COMMON MOORHEN with an adult in the small pond southwest of the > "pump > > house," an adult male HOUSE SPARROW entering a CLIFF SWALLOW nest on > the north > > side of the "pump house," Bonaparte's Gulls (6-8, mixed in with a couple > > different flocks of Forster's Terns), at least three alternate plumaged > SHORT-BILLED > > DOWITCHERS (with a large mixed group of MARBLED GODWITS and WILLETS), > three > > male CINNAMON TEAL, a male NORTHERN SHOVELER and an injured (bad foot) > alternate > > plumaged WESTERN SANDPIPER. > >Would alternate-plumaged Dowiitchers at this time of year be birds that >never went to their breeding grounds, or failed breeders, or what? Are >they at all typical at this time of year? Al, Bob, birders I think that the confusion here is due to the use of terminology. To simplify things the paper one needs to read to really understand all of this plumage stuff is the following as it defines the system we now use in North America. Humphrey, P.S. and K.C. Parkes. 1959. An approach to the study of molts and plumages. Auk 76: 1-31. A visual and extremely useful guide is a note that some friends from Ontario put together for publication in the provincial magazine http://www.ofo.ca/plumages.htm The Humphrey and Parkes system attempts to get away from naming plumages depending on the time of year or breeding state but seeks to name plumages that are homologous with each other in different species. They wanted a system that would allow for a more objective and cleaner manner of studying moult and plumage evolution. Breeding plumages in the Humprey and Parkes system are termed 'alternate' plumages. Actually its not quite this simple as some species can go through three different moults in a year and then you need to match 'homologous' plumage types in order to name them, but the generality applies most of the time. Those dowitchers probably showed some reddish or orange on the underparts, therefore they had moulted or were moulting into an 'alternate' plumage. However this alone does not mean that they were breeding adults (definitive alternate). Most likely these birds were in their first year (first alternate), as most of our oversummering and non-breeding shorebirds are. A careful look at the extent of coloured feathering, as well as wear state of the primaries would probably allow one to differentiate between definite alternate (breeding plumage adults) and first alternate (first spring birds with some breeding type feathers) plumages. Its too early for failed breeder dowitchers to show back down here. Maybe in a couple of weeks we could see some failed breeders back, immediately before the larger push of adult females. I think that Bob saw enough breeding plumage on the dowitchers to call them 'alternate' but Al wants to know if they were 'definitive alternate' or 'first alternate' as that would help him answer the questions he posed. >As to the Black-bellied Plovers, I'm virtually certain there couldn't be >any juveniles here at this time. Perhaps 1-year-old birds. Check out that online paper noted above. Al is correct, there are no juvenile Black-bellied Plovers in the area right now. Juvenile is a term with a very specific meaning, it is the first non-down plumage in a bird. Most birds, particularly passerines, keep the juvenile plumage for an extremely short period of time. Larger non-passerines like Arctic breeding gulls, pelicans, some terns and so forth can keep juvenile plumage for a long time. Black-bellied Plovers are on nests right now, the chicks have not hatched, so this year's batch of juveniles are not with us yet. When those first youngster plovers come back later on in the summer, we will see them in juvenile plumage. Once the juveniles return a few will start moulting in upperpart feathers during their first fall and winter, this is the first prebasic moult, and takes them into first basic plumage. The jury is still out on whether this moult continues into the spring or if there are two moults in the first cycle (see the back cover of the latest Western Birds). In any case those 'winter' plumaged Black-bellied Plovers we see here now, and even some with a smattering of black feathers on the belly are the same age - just under a year old. They have gone through one or two moults and are therefore not in juvenile plumage any longer. Wether they are in first basic or first alternate needs to be resolved by the moult watchers. take care Al Alvaro Jaramillo Biologist San Francisco Bay Bird Observatory P.O. Box 247 Alviso, CA 95002 (408)-946-6548 http://www.sfbbo.org/ [[email protected]] _______________________________________________ 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]]