I spent some time this morning looking over references. “The Birds of the Western Palearctic” (Volume IV, 208-219) gives lots of detail on geographical variation in Black Guillemots. According to this work (pp. 218-219), white tips to the secondaries are absent in races other than the northernmost breeders mandtii and ultimus. This reference lumps ultimus, of high arctic North America and northwest Greenland, with mandtii, which breeds through Labrador, northern newfoundland, both coasts of Greenland, Jan Mayen, Svalbard, Wrangel Island, and Alaska).
It also corroborates the trend toward shortest bills and whitest juvenal and non-breeding plumages among arctic breeders, reaching an extreme in ultimus. Sibley’s Arctic birds are depictions of the “mandtii group,” presumably inclusive of ultimus. <http://www.sibleyguides.com/about/the-sibley-guide-to-birds/subspecies-names-in-the-sibley-guide-to-birds/> Sibley depicts the white secondary tips of the Arctic juvs but doesn't make it completely clear that Atlantic juvs lack them. For one more bit of the puzzle, I’ve posted a video grab of the Southampton bird’s underwing pattern in comparison to underwing of an adult atlantis/arcticus from Massachusetts: http://picasaweb.google.com/tixbirdz/Various2009# The Southampton bird matches BWP’s verbal descriptions of mandtii (or even ultimus), and Sibley’s depictions of the mandtii group, very well indeed. The fifth edition of the AOU Check-list assigns the birds that typically occur in our region to the subspecies atlantis, and Sibley names the “atlantis group,” presumably inclusive of arcticus, as the model for the darker forms he illustrates. Regarding the local situation on Long Island and southern New England, I can’t find any indication that people have proposed that mandtii or ultimus have occurred here previously. Instead, the various discussions of subspecies involve debates over whether the southernmost birds (atlantis) are consistently diagnosable with respect to the widespread arcticus (southern Greenland, Britain, and Scandinavia), or even with respect to nominate grylle of the Baltic Sea. For instance, Bull (1964 & 1974) regarded atlantis as poorly differentiated from arcticus, and Ken Parkes, in his doctoral dissertation, explained that the main feature distinguishing atlantis from grylle was wing length, with considerable overlap (pp. 253-255). To sum up, it seems that the high arctic breeders (mandtii and ultimus) are very different from more southerly breeders (atlantis, islandicus (Iceland), faeroeensis (Faeroes), and grylle); and that the widespread catch-all arcticus (southern Newfoundland, southern Greenland, Britain, Scandinavia) is somewhat intermediate between the two groups, but decidedly closer to the darker, longer-billed southern breeders. Shai Mitra Bay Shore Think green before you print this email. -- 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/ --
