North American Birds

VOLUME 68 NO4 2015

A Quarterly Journal of Ornithological Record Published by the American Birding Association. The mission of the journal is to provide a complete overview of the changing panorama of our continent’s birdlife.

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462 n o r t h a m e r i c a n b i r d s w e s t e r n m a r s h w r e n i n n o va s c ot i a whom suggested that the wren was of the In- terior Western subspecies group. Leukering commented that the "entirely brown crown [...] is not matched by any population of Eastern Marsh Wren with which I have ex- perience." Mlodinow concurred, calling it "a western bird with plain auriculars, paler col- oration overall, and broad pale bars on the tail." All suggested that laingi was most likely to be the subspecies involved. Vagrancy of Western Marsh Wren in the American East has been very little studied. Phillips (1986), whose treatment of Marsh Wren subspecies is exhaustive, indicates that Marsh Wren is generally considered a vagrant to Nova Scotia, with two speci - men records assigned to nominate palustris (3 November and 31 December) and "acci- dental" status for dissaëptus, although Tufts (1969) had noted that this subspecies breeds in marshes near the New Brunswick border. Phillips (1986) adds, without elaboration: "Nova Scotia strays are amazingly variable," and Tufts (1969) had earlier noted that one stray palustris had been diagnosed by Ken - neth Parkes as showing "evidence of inter- gradation with waynei." In western Virginia, a single pallid, brown-crowned Marsh Wren observed near Lyndhurst, Augusta County 11 October 1995 (E. S. Brinkley, C. Cabe), found during a large fallout of migrating but brighter than plesius." He describes the larger plesius as "paler and duller above and on fanks than SW races, iliacus, etc.; up- per tail-coverts usually discernibly (though fnely) barred with dusky. Crown duller [...] and the brown paler, sandier; nape usu- ally conspicuously brown." And he describes pulverius as "still paler and duller (less rufes- cent) even than plesius, and with little or no trace of its slight brownish chest-band (in fresh plumage)." In pulverius and plesius, the uppertail coverts are barred, unlike in the Miners Marsh bird. In pulverius, the fanks are rather pale (unlike in the Miners Marsh wren), while in plesius, the fanks are typi- cally medium brown. Roberson (2015) in - dicates that of the Interior Western group, laingi shows greatest amount of contrast in plumage and most colorful tones, and in fact the browns of crown, uppertail coverts, scapulars, and fanks were washed with ru - fous in the Miners Marsh wren. Thus laingi is perhaps the most likely subspecies involved in the case of the Miners Marsh wren, which showed tones rather richer than seen in most photographs of freshly plumaged pulverius. However, a plesius lacking barring in the up- pertail coverts is also conceivable. Photographs of the Miners Marsh wren were provided to Ian McLaren, Peter Pyle, Tony Leukering, and Steven Mlodinow, all of verius, plesius, and laingi. These subspecies have ranges currently described (Pyle 1997, Kroodsma and Verner 2014, Roberson 2015; Figure 1) as follows: • laingi breeds from east-central British Co- lumbia to northeastern Montana, North Dakota, to central South Dakota; it win - ters south through New Mexico and Texas to central Mexico. • plesius breeds from southeastern Idaho and western Wyoming through Utah, Col- orado, and western Nebraska; it winters from Kansas to Texas and Mexico. • pulverius breeds from central British Co- lumbia through Great Basin, south to east- ern California and Nevada, east to west - ern Montana; it winters in Arizona, New Mexico, western Texas, and Mexico. The subspecies laingi has the most north- erly/easterly breeding range of the Interior Western group and is strongly migratory; this subspecies co-occurs with iliacus (now placed with the Eastern group) in the Great Plains. The subspecies plesius breeds south of laingi, and pulverius breeds farther west still. Plumage distinctions among the Inte- rior Western subspecies are subtle. Phillips (1986) describes laingi as "palest brown" above, "brightest, most rufescent or buffy," with pale fanks, "less rufescent than iliacus Figure 2. Comparison of the Marsh Wren at Miners Marsh 11 October 2014 (left) with a Marsh Wren found on Seal Island, Nova Scotia 11 October 1998. The bird on the right has plumage features consistent with subspecies dissaëptus of the Eastern Marsh Wren group, known to breed in the marshes as near as the New Brunswick/Nova Scotia border region. The crown of the Seal Island bird is much blacker, contrasting with white supercilium, which contrasts with rufous auriculars. Its uppertail coverts and scapulars are intensely rufous-brown, and its fanks are nearly as richly colored. By contrast, the Miners Marsh wren has a brown crown (with rufous tones) contrasting less with a sandy supercilium; its auriculars are rather pale, lightly washed with rufous, providing weak contrast with the supercilium. In the Miners Marsh wren, the dusky tail bands are narrower and less blackish than in the Seal Island bird, enhancing the general impression of a paler, browner bird overall. Pyle (1997) notes that the rectrices are replaced in preformative molt, and this image does appear to show replaced rectrices; thus, even if the bird is in formative plumage, its tail would probably look very similar in defnitive basic plumage. Photographs by Alix A. d'Entremont (left) and Richard Stern.

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