For more information on the degree of separation of races of Black, Pigeon and Spectacled Guillemot, there is a paper by Kidd and Friesen titled "Sequence Variation on the Guillemot (Alcidae: Cepphus) Mitochondrial Control Region and its Nuclear Homolog". Most of it is beyond me, but I think the authors present evidence that with an average sequence divergence of 0.61%, populations of Black Guillemots are not as clearly segreated as populations of Snow Goose (6.7%) or Grey-crowned Babbler (8.0%), probably due to recent divergence within the species.
Mike Cooper Ridge, LI,NY ----- Original Message ----- From: Angus Wilson To: NYSBIRDS-L Sent: Tuesday, December 22, 2009 11:52 PM Subject: Re: [nysbirds-l] Fw: Southampton Black Guillemot Photo Shai Mitra is absolutely right in drawing our attention to the extent of the white on the upperparts and head of the Peconic Bay Black Guillemot. I've only seen the one photo by Luke Ormond and hope there are some more. Even allowing for bright lighting (sunlight and snow glare) it would appear that this bird lacks the typical dark mottling on the crown, nape and upper wing coverts of an adult or first-winter. Pigeon Guillemot (the Pacific counterpart of the Black Guillemot) is safely ruled out by the lack of a dark wedge in the white scapular patch). As Shai mentioned, birds from the eastern Canadian Arctic, NW Greenland and across to Spitzbergen (_ultimus/mandtii_) are much whiter than the more southerly population (_arcticus_) that breeds in the Gulf of St. Lawrence and Canadian Maritimes and winters down the coast to New England and Long Island (occasionally). Birds from the eastern Canadian Arctic have shorter bills relative to wing length than those from further south. It gets a bit confusing when you consider birds from the British Isles (sometimes included with _arcticus_), which tend to be shorter billed, but I agree the COMBINATION of snowy white plumage and short bill is strongly suggestive of _ultimus/mandtii. Good profile shots may allow us to assess bill length further by comparing various ratios. While some recent authorities (e.g. Gaston & Jones 1998) consider these populations relatively distinct and non-clinal, New York's eminent authority John Bull was rather dismissive of the taxonomic divisions (see Birds of the New York Area 1964). In Bull's defense, it may be that the differences between _arcticus_ and the various European populations had not been teased out at this time. Bull (1976) mentions only two extant specimens (3 Jan 1918, Orient, Suffolk Co., collected by Roy Latham, NYSM speciment 25005 and 27 Nov 1949, Quogue, Suffolk Co., collected by B. Frederico, AMNH specimen 348699), both of which he declined to assign to a particular subspecies. Have additional specimen have been gathered in the interim? Regardless, most sight records in New York waters evidently refer to relatively dark southern birds, likely _arcticus_. Given the exciting possibility that this bird is from a different population (quite possibly unrecorded in NY State), I would strongly encourage observers to submit any photos they have to NYSARC for further review. -- Angus Wilson New York City & The Springs, NY, USA http://birdingtotheend.blogspot.com/ ------------------------------------------------------------------------------ No virus found in this incoming message. Checked by AVG - www.avg.com Version: 8.5.430 / Virus Database: 270.14.117/2583 - Release Date: 12/23/09 08:28:00 -- NYSbirds-L List Info: http://www.NortheastBirding.com/NYSbirdsWELCOME http://www.NortheastBirding.com/NYSbirdsRULES Archives: 1) http://www.mail-archive.com/nysbirds-l@cornell.edu/maillist.html 2) http://birdingonthe.net/mailinglists/NYSB.html Please submit your observations to eBird: http://ebird.org/content/ebird/ --
