From south-bay-birds-bounces+south-bay-birds-archive=[[email protected]] Sat Sep 27 15:45:00 2003 Received: from www.plaidworks.com (localhost [127.0.0.1]) by plaidworks.com (8.12.9/8.12.9) with ESMTP id h8RMfSIC004154 for <[[email protected]]>; Sat, 27 Sep 2003 15:41:28 -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 h8RMejZP004111 for <[[email protected]]>; Sat, 27 Sep 2003 15:40:45 -0700 (PDT) Received: from computer.comcast.net (12-234-255-153.client.attbi.com[12.234.255.153]) by comcast.net (sccrmhc11) with SMTP id <2003092722404401100539vde>; Sat, 27 Sep 2003 22:40:44 +0000 Message-Id: <[[email protected]]> X-Sender: [[email protected]] (Unverified) X-Mailer: QUALCOMM Windows Eudora Version 5.2.1 Date: Sat, 27 Sep 2003 15:40:21 -0700 To: "Dr. Michael M. Rogers" <[[email protected]]>, [[email protected]] From: Alvaro Jaramillo <[[email protected]]> Subject: Re: [SBB] more golden-plover fun 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 11:25 AM 9/23/2003 -0700, Dr. Michael M. Rogers wrote: >More golden-plover discussion - delete if bored to tears :) Delete again if further bored to tears. >1) All the visible primaries on this bird (I did not see it in flight) >are old brown feathers - it is apparently not in primary molt. I did >look for how close the outermost two primaries were in length and they >were close, although the difference was visible. Is there a >diagnostic difference in this character? If so, how much longer >should the outermost feather be in AMGPL? I am not sure about this feature, I need to start collecting up photos. What I do know is that the American Golden has a longer and apparently more pointed wing. This is likely a general difference, and probably not fully diagnostic. The more pointed wing of the American should show up as slightly longer distances between primaries, with the longest being 'noticeably' longer than the next one. Again, I am unsure as to how one interprets primary spacing. I do think it is important and will be different between the two species, but the standard patterns have to be determined by age group as I expect that it will also differ between juveniles and adults. In other words I Dunno? >3) The bird in your second photo at >http://chucao.home.comcast.net/pgpl2.jpg does indeed appear to have a >surprisingly long wing extension past the tail tip. On the other >hand, the tail look surprisingly short (perhaps in molt?). If that >extension is real then it certainly does seem to approach that of the >Alviso bird. On the other hand, my experience with adults of both >species in Alaska and Hawaii (not just juveniles on migration down >here) has not turned up PGPLs with such long wing extension past the >tail. This bird was photographed in January, by this time I would expect all tail moult to be done with in Pacific Golden Plover. >4) I am not sure that your wing extension lines in Tom's photo at >http://chucao.home.comcast.net/pgpltom1.jpg are accurate. On my >monitor I see what I think are primaries further aft than this - >admittedly it's difficult to tell what's wing and what's background. >Certainly it would be nice to get a photo of the bird's right side >that is not foreshortened and in which the wing tip is obvious. What I did is took the original photo from Tom and enlarged it quite a bit in photoshop. I did a lot of fiddling with changing contrasts and brightness to determine where the blackish feathers ended and where the ground behind started. What appears to be a further extension of the wing is actually an illusion due to the patterns on the ground behind the bird. At least that is how I interpreted the additional info I could get by really shifting the contrast levels to the fullest. Those areas beyond the line did not blacken up in the same way as the parts that I interpreted as primaries. I could certainly have done this incorrectly, and maybe someone else could go and confirm or refute my interpretation. >5) As a result of your museum work, did you find diagnostic plumage >differences between basic and alternate upperpart feathers or are your >noted differences just general tendencies? Your photo of the adult >male AMGPL in full breeding plumage clearly does have a different look >to the upperparts. But do all birds look like this? Is it possible >to definitively say that the long tertial on the right side of the >Alviso bird is a new basic feather based on the narrow pale edge and >minimal notching? Or are patterns in alternate and basic plumage >subject to much overlap? Looking at Joe Morlan's mystery >golden-plovers at http://fog.ccsf.cc.ca.us/~jmorlan/oct99.htm, I >certainly see a greater mix of white and gold edges that do suggest a >more alternate or transitional type pattern than that of the Alviso >bird. There are consistent differences between basic and alternate feathers that are certainly diagnostic in males, perhaps less so in females. There are also general differences between the alternate feathers of American versus Pacific golden plovers, with Americans having more of a tendency to show white at the feather tips than Pacifics. I would need to go and look at the specimens again to really get detailed information on this, because when I went through the exercise I only jotted down some very general notes rather than the nitty gritty specifics. Whatever the differences are, at this time of year the most valuable set of information you can use is the wear state to separate new basic feathers from the old alternate ones. This will not fail, particularly if you can see examples of each type on the bird. I do think that the birds on Joe's site are much more intermediate in plumage than the Alviso bird. >6) Lastly, before locating the plover on Sunday, I heard a plover >"too-eee" call that I presume came from the bird (it was not a >Semipalmated or Black-bellied call). The Tundra Plovers book >apparently lists "TUli" for AMGPL and "tjuitt" for PGPL, but other >references suggest complete overlap in calls - so perhaps this means >nothing. I don't know. What I have been doing is diligently recording voices of both forms whenever I can. So far I have a bunch of recordings of Pacifics from Hawaii, some Americans from Chile, and a few more from Argentina. I have not gone through the recordings and made sonograms of the calls, mainly because I know I will be getting more in the coming year and wanted to sit down with a larger sample size to make the whole thing worthwhile. Just as an opinion they do seem to sound different to me, but I am not willing to stick my neck out right now and say exactly how they differ as I could be entirely wrong and don't want to mislead. I haven't sat down and listened to the two back to back to teach myself to differentiate between the two, so even if I heard one I wouldn't necessarily be able to say which one it was. Another point to think about is that when the plovers fly over and call normally this call type is different from the more agitated calls that they give when they take off due to some kind of disturbance. I have recorded both call types, so at least I have some measure of variability within each species, and it is likely that variability that makes it difficult to categorize the two species vocally in the field. Given that the two differ substantially in all their display vocalizations, I would be amazed if they don't differ in their flight calls too. If my comparisons are informative I hope to publish a short note on them somewhere, but this will be in the future sometime. >I Guess I now have a good excuse to go study this bird some more :) It is the joy of birding! cheers Alvaro 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]]