North American Birds

VOLUME 70 NO3-NO4 2019

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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257 V O L U M E 7 0 ( 2 0 1 9 ) • N U M B E R S 3 / 4 RED-BACKED SHRIKE IN ALASKA ger and thinner tail, and no plumage shows flanks as pale as the Gambell bird. Juvenile Tiger Shrikes do not have a mask as strongly defined as the Gambell bird, lack blackish centers to the tertials, and the underparts are saturated with yellow. • BROWN SHRIKE: Four subspecies of Brown Shrike have been recognized, of which the nominate, northern-breeding subspecies (L. c. cristatus) is the only one confirmed with weakly separate subspecies. Isabelline and Brown shrikes are polytypic, with the nominate northern subspecies in each case being most similar to Red-backed Shrike and most likely to reach Alaska. Our analysis in - corporates differences among these taxa for birds in mostly juvenile body feathering and with juvenile flight feathers. Seminal works that deal with the identification of these taxa include Svensson (1992), Cramp and Perrins (1993), Worfolk (2000), Panov et al. (2011), and Pyle et al. (2015), and these sources were relied upon heavily in our identifica- tion. Additional helpful sources include Message (2001; first-year Turkestan Shrike) and McKee (2017; Brown Shrike). The Gambell bird was clearly a member of this species assemblage. Two other Asian shrikes, Bull-headed Shrike (L. bucepha- lus) and Tiger Shrike (L. tigrinus) are larger headed and have obviously shorter primary projections. Bull-headed Shrike has a lon- litt.) and the unbarred formative upperpart feathers and blackish feathers of the lores and auriculars may also support its being a male. Most of the tertials appear to be dark brown or blackish-brown in the Gambell bird rather than the more expected rufous- brown (fig 1-3 and 6). At least three juvenile Red-backed Shrikes from Korea studied by Moores showed similar-looking tertials. It may be that some juvenile male Red-backed Shrikes show darker than typical tertials. Identification Here we provide a detailed analysis of the plumage and wing and tail morphology of the Gambell shrike, confirming our iden- tification as Red-backed Shrike. Most au- thorities recognize Red-backed, Turkestan, Isabelline (L. isabellinus), and Brown shrikes as four separate species within an assemblage (Pyle et al. 2015). Red-backed and Turkestan shrikes are often considered monotypic or Figures 7A–D. Various calculations of wing and tail morphol- ogy ratios have been shown to be useful in the identification of Eurasian shrikes. These images and annotations indicate some of the morphological characteristics and measurements that were considered. These ratios—particularly in combina- tion—clearly eliminated Brown Shrike and better fit Red- backed than Turkestan Shrike. Also note the light buff wash to the undertail coverts—particularly visible in 7D—a feature shown by many young Red-backed Shrikes. Full images of the bird in A are shown in Figure 3, and of C in Figure 5. Photos by © Sue Bryer (A, C, and D) and © Brad Benter (B) p. covs b a p9 a/b = 0.149 p8 A C B D d c r6 r5 c/d = 0.132 tail base tip (r1) d c r6 r5 c/d = 0.153 tail base tip (r1) p. covs b a p9 a/b = 0.127 p6 not emarginated p8

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