North American Birds

VOLUME 69 No1 2016

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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Figure 1. The Mendocino shrike when frst observed on 5 March 2015 (a) and last observed on 22 April 2015 (b). Despite low resolution, these images demonstrate substantial change in plumage due to body- feather molt over the period of observation, especially in the color of the crown, head, and sides to the underparts. Photographs by Alison Cebula (a) and Murray Brown (b). 5 V O L U M E 6 9 ( 2 0 1 5 ) • N U M B E R 1 T H E M E N D O C I N O S H R I K E T he Mendocino County, California shrike is one for the ages. It was studied care - fully by numerous observers, and over the course of its eight-week stay, it was undergoing and nearly completed its preformative molt. As it molted, the colors of its plumage changed, confounding its observers, who turned to Old World shrike experts for clarity. With the ex - ception of collecting the bird itself, every tool in the arsenal of the amateur and professional ornithologist has been brought to bear in the quest for an identifcation: photography, audio recording, specimen study, molt study, exten - sive correspondence, and an exhaustive re- view of the literature from across Eurasia. The product of this effort is a most unexpected but well-grounded conclusion: that the shrike was a hybrid of two Eurasian species, both unre - corded in North America, moreover two spe- cies whose zone of hybridization lies in central Asia, a part of the world that has sent few va - grants to North America: Greater Sand-Plover (Charadrius leschenaultii), Blyth's Reed Warbler (Acrocephalus dumetorum), Sedge Warbler (A. schoenobaenus), Lesser Whitethroat (Sylvia cur - ruca), Spotted Flycatcher (Muscicapa striata), and Common Redstart (Phoenicurus phoenicu - rus). Although the identifcation was diffcult, and is by no means certain, its complexity provides the thoughtful birder with a sense of great humility but also great hope in our quests to identify birds utterly unfamiliar to us. Abstract The Red-backed (Lanius collurio), Turkestan (or Red-tailed, L. phoenicuroides), Isabelline (L. isabellinus), and Brown (L. cristatus) Shrikes comprise an assemblage of related species that breed, migrate, and winter throughout the Old World. The group includes fve or more subspecies, and hybridization between Red- backed Shrike and each of the other species is known to occur. An individual of this as - semblage was observed at the mouth of Alder Creek, Mendocino County, California, from 5 March through 22 April 2015. In an effort to identify this shrike, we analyzed more than 500 digital images and examined more than 900 specimens to assess variation in molts, plumages, and age/sex-determination criteria within the species assemblage. We also com - pared recordings of the Mendocino shrike's 1a 1b

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