From south-bay-birds-bounces+south-bay-birds-archive=[[email protected]] Thu Jul 31 10:02:54 2003 Received: from www.plaidworks.com (localhost [127.0.0.1]) by plaidworks.com (8.12.9/8.12.9) with ESMTP id h6VH0SFe017565 for <[[email protected]]>; Thu, 31 Jul 2003 10:00:28 -0700 (PDT) Received: from sccrmhc11.comcast.net (sccrmhc11.comcast.net [204.127.202.55]) by plaidworks.com (8.12.9/8.12.9) with ESMTP id h6VGx9kK017517 for <[[email protected]]>; Thu, 31 Jul 2003 09:59:09 -0700 (PDT) Received: from computer.comcast.net (12-234-255-153.client.attbi.com[12.234.255.153](untrusted sender)) by comcast.net (sccrmhc11) with SMTP id <2003073116590801100o3r0pe>; Thu, 31 Jul 2003 16:59:08 +0000 Message-Id: <[[email protected]]> X-Sender: [[email protected]] (Unverified) X-Mailer: QUALCOMM Windows Eudora Version 5.2.1 Date: Thu, 31 Jul 2003 09:59:01 -0700 To: "Tom Grey" <[[email protected]]>, [[email protected]] From: Alvaro Jaramillo <[[email protected]]> Subject: Re: [SBB] Palo Alto Baylands puzzlers, 7-30 In-Reply-To: <[[email protected]]> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed 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 09:00 AM 7/31/2003 -0700, Tom Grey wrote: >At Palo Alto Baylands last evening 6-7 the light was good and some >migrating birds ventured close enough to the footpath by the boathouse for >me to get a few decent digiscopes -- issues with three of them. THESE ARE GREAT PHOTOS TOM! >1. OK, I'm an immature-gull dummy, but what the heck is this? > >http://www.geocities.com/tgrey41/GullQuery.jpg > >My best guess is, juvenile Ring-billed Gull already molting to first-winter This is one where more photos from other angles would be helfpul. There are aspects of the look of the bird that suggest California Gull (bill pattern for example) but I think that its just from a misleading angle on the bird. The large bill, beady and centrally placed eye, bulky body all suggest Glaucous-winged Gull. I will disagree with Mike on the primary darkness though. Young Glaucous-winged Gulls primaries are variable, but if they are retained to this point (practically a year old) they fade to nearly white. Any distinct brown or dark tone on primaries at this time of year suggests to me that it is not a pure Glaucous-winged Gull, but rather a hybrid Glaucous-winged x Western Gull. A mix that is known as "Puget Sound Gull" in some circles. The age given the amount of grey on the upperparts, bill colour and so fourth is third calendar year, so hatched in summer of 2001. Tom is correct in nothing that on the smaller gulls, such as Ring-billed the grey upperparts are gained during the first summer and fall (Hatch Year), this happens a year later in larger gulls. However, juveniles are just becoming apparent right now in the Bay Area (Ring-bills, Californias, Westerns) and their moult has not yet started, or if it has only one or two grey feathers (on a Ring-billed Gull) will be apparent in late July/early August. Another trick that juvenile Ring-billed and California gulls play is that they fledge with entirely black bills, and some individuals may keep these colours a couple of weeks into their life. Later on of course both of these gulls have pale based bills with dark tips, and many juveniles right now already show this pattern, but not all do! Do you have other shots of this bird? >2. Here's a Long-billed Curlew. Can I say for sure adult (in which case >probably male, the shortish bill)? I think the coverts are barred, which I >read in Paulson is diagnostic of adult plumage. > >http://www.geocities.com/tgrey41/LongbilledCurlew3.jpg In terms of Hatch Year (juvenile) versus After Hatch Year (older than a year) you are right, this is an adult (After Hatch Year) based on coverts, and also on those worn primaries. A juvenile would have crisp, new primaries. If you want to get even more into this, there is a first year plumage as well but I have no idea on how to age a bird as such at this time of year. Earlier in the season, in June before the southbound adults have arrived most of the LBCU that we have over summering are immature birds (Second Calendar Year in banding terms). In general they have more worn primaries than adults, and there may be some retained coverts (juvenile) on the wings. Bill is short on this bird, so you are safe calling it a male. In shorebirds the longer-billed the species, the greater the degree of bill length difference between sexes and the smaller amount of overlap, so the easier to sex visually in the field. Also the other rule is that females have longer bills in (all?) shorebirds. >3. Here's a Semipalmated Plover. Can I say for sure it's a male, on the >basis of the strongly black markings? > >http://www.geocities.com/tgrey41/SemipalmatedPlover2.jpg Probably. This feature is a real variable one. Males average blacker on their face and neck markings, but there is a great deal of overlap. You can say that it was probably a male, but not for sure. Note the thin yellowish orbital ring, this is a feature few people look for but it is diagnostic for separating from Ringed Plover. Your bird is indeed a Semipalmated! Not useful information now, but someday you may we thinking you are looking at a Ringed Plover and it could come in handy. Juveniles show the orbital ring, but it is much less distinct and may not be visible on all Semipalmated Plovers. cheers 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]] ***** NOTE NEW E-MAIL ADDRESS**** _______________________________________________ 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]]