North American Birds

VOLUME 70 NO1 2017

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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V O L U M E 7 0 ( 2 0 1 7 ) • N U M B E R 1 9 A M E T H Y S T - T H R O AT E D H U M M I N G B I R D I N Q U É B E C the feeder, before retreating to the surround- ing woods, notably on finer branches of white spruce, Picea glauca, and white birch, Betula pa- pyrifera. The favorite perch of the hummingbird was a northern white-cedar, Thuja occidentalis. Visits were spaced by thirty-minute intervals on July 30, but were increasingly wide apart on July 31, when the birds was last seen at sunset. Discussion The Amethyst-throated Hummingbird is found in highlands from Mexico to El Salvador and central Honduras. Taxonomy is complex; four to six sub- species are recognized depending on the authors. The nominate, magenta-throated subspecies am- ethystinus is found on both slopes of the Sierra Madre Oriental from the states of Nayarit and Tamaulipas to the states of Morelos and Mexico, with populations in the western half sometimes regarded as another subspecies, brevirostris. The distinctive, violet-blue–throated subspecies mar- garitae is found in the mountains of southwest- ern Mexico in Michoacán, Guerrero, and western Oaxaca (Howell and Webb, 1995). Reddish- purple–throated populations from Chiapas and Guatemala are often considered as another sub- species, salvini, while populations of Honduras would be of the darker, more-contrasted nobilis subspecies. Finally, circumventus occurs in south- ern Mexico, in southwestern Oaxaca, is similar to nominate amethystinus, and is doubtfully distinct (Edmunds et al. 2011, Clements et al. 2016). From available resources, the "best match" case for this hummingbird, based mainly on gorget color, would be with the nominate subspecies. In spite of the weak-seeming local phenotypic variation, Cortés-Rodriguez et al. (2008) found deep genetic divergence between northern (L. amethystinus) and southern (L. salvini) clades separated by the Isthmus of Tehuantepec. That could possibly warrant separate species status as originally proposed by Ridgway (1911). Aging hummingbirds is notoriously difficult, and this individual is no exception. The gorget is full, and relatively fresh, with broad grayish edges to all feathers. Two generations of mantle feathers are noticeable on the hummingbird's backside, but this is not necessarily definitive in distinguishing between HY (hatch-year) or AHY (after-hatch-year) status for the bird. No evidence of primary molt is visible, and the plumage is Fig. 4. This bird defied attempts to definitively determine age. From behind, it clearly showed two generations of feathers in its back, though this is not a sure way to distinguish between younger and older birds. On the other hand, the full gorget and lack of molt in the primaries may suggest an after-hatch-year bird, but without more concrete knowledge on the species' breeding and molt cycles, this is purely speculation. © Photo by © Annie Lavoie.

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