Date: Tue, 4 Jun 2002 10:40:01 -0400 Reply-To: Maryland Birds & Birding Sender: Maryland Birds & Birding Comments: RFC822 error: MESSAGE-ID field duplicated. Last occurrence was retained. From: Harvey Mudd Subject: Re: Pacific Loon Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" To expand on Tyler Bell's posting of yesterday regarding chin straps in Arctic Loons, I note that the Birding World (8: 458-466, 1995) article I cited in my prior message was written from the European pointy-of-view - i.e. how could one identify a potential vagrant Pacific Loon among the Arctics of Europe. This article considered both races of Arctic: viridigularis and arctica (the race that breeds from Northern Europe to Western Siberia). Although this article distinguishes between viridigularis and arctica for certain features (e.g. the color of the fore-neck patch on adults in breeding plumage), no such distinction is make with regard to the chin strap. Indeed the remarks on chin strap are virtually identical to those I quoted yesterday from the Birding article. This article includes three large photographs of Artic Loons (termed "Black-throated Divers), two juveniles taken in England (Plates 7 and 8) and one first summer adult taken in Sweden (Plate 9). These may be presumed statistically to be arctica arctica. At the very most, with much imagination one could think that traces of chin strap are visible in perhaps two of these photos, but in neither case is it as prominent as even the rather faint one seen on the alternate plumage Pacific Loon photoed in California (Plate 4). There does seem to be a difference between Birch and Lee and Jonsson on this point. Tyler does not mention the age of the arctica shown by Jonsson with a chin-strap. Could this feature become more prominent with age, or is the Jonsson bird an exception? I can say nothing on the basis of personal experience, never having seen an Arctic Loon to my own satisfaction. In any case, there seems to be no one maintaining that the Clopper Lake loon is Arctic rather than Pacific. Harvey Mudd Jane and I also did a little research on Arctic vs. Pacific using available material at home. Harrison's Seabirds is less than useful as it classifies Pacific as a subspecies of Arctic. Maybe there's a newer edition after the split of Pacific from Arctic. The fairly comprehensive ID article in Birding vol. 29:3 1997 deals specifically with viridigularis, the Siberian subspecies of Arctic Loon which would be more likely to show up in Alaska or along the west coast. Lars Jonsson's "Birds of Europe" deals with the nominate subpecies arctica which would be the more likely bird to show up on the east coast. Jonsson shows Arctic Loon with a chin strap which is definitely contradictory to the Birding article. Apparently the viridigularis subspecies doesn't have a chinstrap. On Pacific Loon, the auricular is dingy whereas on Arctic Loon, the auricular is clear white to behind the eye. Also, the head shape on Arctic is more angular or boxy whereas Pacific is smooth. The white on the flank of Arctic is apparent in all plumages and Sibley states that this distinguishes it from all other loons. When Jane and I reviewed our couple of minutes of video, the white patch on the flank is visible sometimes but a various angles, it disappears entirely. Also, the head shape is smooth which is clearly apparent in Dave Czaplak's photos. So, as much as I'd love this to be an Arctic Loon, which would be a lifer, I'd have to say it truly is a Pacific Loon. And, in the absence of Phil Davis, I'd like to state that Pacific Loon is a review species anywhere in Maryland so please document your sightings! Tyler Bell bell@acnatsci.org California, MD Wave that flag...wave it wide and high! Grateful Dead, U.S. Blues >>> shm@CODON.NIH.GOV 06/03/02 10:11AM >>> Bob, While Jim Stasz, Marion and I were admiring the Clopper Lake Pacific Loon last week we carefully noted the width, length and shape of the white flank patches. I have to admit that my mind was fantasizing about the possibility of seeing Maryland's first Arctic Loon. However, upon returning to the car a few minutes later, a recheck of the articles by Andrew Birch and Cin-Ty Lee in Birding 29, 106-115, 1997 and Birding World 8, 458-466, 1995 - both devoted to field identification of Arctic and Pacific Loons, and how to distinguish them, and each with many photos - confirmed that the flank patches we had just seen on the loon in question were entirely compatible with Pacific, and not with Arctic. As summarized (p.111) in the Birding article, "Pacific Loons can show obvious white above the waterline if they are swimming "high" or partly rolling over as if to preen, but they never show the shape and extent of white that Arctics display (Dunn and Rose: Birding 24, 106-107, 1992). The key is to note whether the white on the flanks extends up to the sides of the rump, indicatiing an Arctic Loon". That is, on the Arctic the posterior white patches "flare" to a greater extent above the waterline, rather than forming a straight boundary between the dark sides and the undersides. These features are seen in many of the photos in these articles. Plate 3 in the Birding World article shows an adult summer Pacific Loon with rather broad white flank patches, but they extend only about 60% of the distance from the mid-base of the neck towards the rear, and do not "flare" at the back. With respect to the chin-strap (which we did not see well), the Birding article (p.112) says "On adults in basic plumage, a well-defined dusky chin-strap is diagnostic of Pacific Loon (Figure 10). Some Arctic Loons may show a slight dusky chin-strap (or an impression of one), but it is never an obvious, well-defined feature as it normally is in Pacific Loons. The absence of a chin-strap, however, does not necessarily denote an Arctic Loon, because a small percentage of Pacific Loons, particularly juveniles, can have very faint, inconspicuous chin-straps (Schulenberg: Birding 21, 157-158, 1989)". Harvey Mudd ======================================================================= To leave the MDOsprey list, send e-mail to listserv@home.ease.lsoft.com with the following message in line 1: signoff mdosprey ======================================================================= ____________________________________ S. Harvey Mudd NIMH/DIRP/LMB Building 36, Room 1B-08 36 CONVENT DR MSC 4034 BETHESDA MD 20892-4034 tel: 301-496-0681; fax 301-402-0245 email: shm@codon.nih.gov ======================================================================= To leave the MDOsprey list, send e-mail to listserv@home.ease.lsoft.com with the following message in line 1: signoff mdosprey ======================================================================= =========================================================================