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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262 N O R T H A M E R I C A N B I R D S RED-BACKED SHRIKE IN ALASKA Literature Cited BirdLife International. 2017. IUCN Red List for birds. Downloaded from http://www.birdlife. org on 15 December 2017. Cramp, S., and Perrins, C. M. (eds.) 1993. The Birds of the Western Palearctic. Volume 7. Oxford University Press, Oxford. Dickinson, E. C., and Christidis, L. (Eds.). 2014. The Howard & Moore Complete Checklist of the Birds of the World, 4 th ed., vol. 2. Aves Press, Eastbourne. Gibson, D. D., and Withrow, J. J. 2015. Inventory of the species and subspecies of Alaska birds, 2 nd ed. Western Birds 46(2):94–185. Gill, F., and D. Donsker (Eds.). 2017. IOC World Bird List (v 7.3). doi: 10.14344/IOC.ML.7.3. Kryukov, A. P., and Gureev, S. P. 1997. New data on interrelations of Red-backed and Brown shrikes (Lanius collurio and L. cristatus, Aves) in the zone of sympatry. Russian Journal of Zoology 4:537–544. Lehman, P. E. 2018. River Warbler (Locustella fluvi- atilis) at Gambell, Alaska: First record for North America. Western Birds 49:136–141. McKee, M. 2017. Brown Shrike, Out Skerries, Shetland, October 2016. In: French, P. The Carl Zeiss Award 2017. British Birds 110:474–475. Message, S. 2001. The Turkestan Shrike in Kent. Birding World 14(10):432–434. Moores, N. 2015. Brown Shrikes and the annual thorny identification challenge! Online article accessed in December 2017 at http://www. birdskoreablog.org/?p=15752 Ornithological Society of Japan. 2012. Check- list of Japanese Birds, 7 th revised edition. The Ornithological Society of Japan, Sanda. Panov, E. N., Cade, T. J., and Woods, C. P. 2011. The True Shrikes (Laniidae) of the World: Ecology, Behavior and Evolution. Pensoft Publishers, Sofia, Bulgaria. Pyle, P., Keiffer, R. J., Dunn, J. L., and Moores, N. 2015. The Mendocino shrike: Red-backed Shrike (Lanius collurio) × Turkestan Shrike (L. phoenicuroides) hybrid. North American Birds 69(1):4–35. Rosenberg. G. H., Lehman, P. E., Lang, A., Stoll, V., and Stoll R. 2018. Thick-billed Warbler (Iduna aedon ) at Gambell, Alaska: First record for North America. Western Birds. 49(3) 226-230. Slack, R. 2009. Rare Birds Where and When: An Analysis of Status and Distribution in Britain and Ireland. Russel Slack Rare Birds Books, York. Svensson, L. 1992. Identification Guide to European Passerines, 4 th ed . Distributed by British Trust for Ornithology, Thetford. Worfolk, T. 2000. Identification of Red-backed, Isabelline, and Brown shrikes. Dutch Birding 22:323–362. n Conclusion In a remarkable fall for Asian vagrants at Gambell which also saw first North American records of Thick-billed Warbler (Iduna aedon; Rosenberg et al. 2018) and River Warbler, the Red-backed Shrike became the first record for the continent when it was ac- cepted by both the Alaska and ABA checklist committees. Identification as a Red-backed Shrike was based on the following features: • Tail morphology (shorter than Brown Shrike, and with broader, longer outer rectrix); • Long primary extension beyond the tertials, with the tip of p6 falling roughly equidistant with p9; • Slimmer bill than Brown Shrike; • Low-contrast face-mask with rusty tones; • Grayish nape, unique to Red-backed Shrike; • Extensive vermiculations on the upperparts and flanks; • Reddish tones to the upperparts, typical of Red-backed Shrike; • Darker central tail feathers unique among these taxa to Red-backed; • Pale underparts, lacking the saturated tones expected in Brown, Turkestan, and especially Isabelline shrikes. The 2017 Gambell bird's appearance and measurements based on field observation and, especially, on an extensive series of pho- tographs, is entirely consistent with a Red- backed Shrike. Brown Shrike is eliminated based on several plumage features and on the wing and tail morphology. Turkestan and Isabelline Shrikes are also eliminated based on both structure and on plumage. Those two species seem more separable in mostly- juvenile plumage than in, for example, for- mative male plumage, such as that shown by the hybrid bird from Mendocino County, California. Acknowledgments Special thanks are due to Brad Benter and, especially, Sue Bryer and Clarence Irrigoo Jr. for their superb efforts in obtaining a series of excellent photos of the Gambell shrike, critical in the proper diagnosis of species. Valuable input on the identification of the Gambell shrike and on the occurrence of various vagrant shrikes was received from Louis R. Bevier, Brian E. Daniels, Doug Gochfeld, Chris Gooddie, Neil Hayward, Lars Svensson, and Thede G. Tobish. Helpful comments on drafts of the manu - script were provided by Sue Bryer and Chris Gooddie. and it winters in southern Arabia and east- ern Africa. Subspecies arenarius and tsaida- mensis are relatively short-distance migrants that breed in northwestern and north-central China and winter in Pakistan and India—and thus are unlikely to be involved in records of vagrants far out of range. Vagrant Isabelline Shrikes have turned up eastward to Japan (no more than three records; OSJ 2012), as well as westward through Europe to the U. K., where several individuals are typically found annually, and once to Iceland; many of these vagrants have not been identified to taxon, although approximately twenty of each have been identified as nominate isabellinus and as Turkestan Shrike (Slack 2009, www.tarsiger. com, www.netfugl.com, https://waarneming. nl ). Bull-headed Shrike is largely a short-range migrant, endemic as a breeding species to East Asia, with birds breeding in Korea, Japan, and eastern China north to eastern Russia, and wintering south to southern China (BirdLife International 2017). Tiger Shrike breeds in Korea and China east and north to the Russian Far East and Japan (where very locally distributed), win- tering throughout much of Southeast Asia south to Indonesia and Borneo (BirdLife International 2017). Misorientation in an approximately 180º opposite direction from normal migratory paths, over northern regions on a great- circle route, may account for the occurrence of many Old World vagrants to Alaska and elsewhere in North America. Such a path would take the average vagrant Red-backed Shrike directly through western Alaska, with a range in vectors fully encompassing the state (Pyle et al. 2015), and we specu - late that this is the most likely path for the Red-backed Shrike reaching Gambell. As Red-backed Shrikes are long-distance mi - grants, wintering primarily in southern Africa, their migration distance would easily take them at least as far as Alaska. Such 180º misorientation theory may explain vagrant North American records of a number of other central Asian species, such as Greater Sand-Plover (Charadrius leschenaultii), Blyth's Reed Warbler (Acrocephalus dume- torum), Sedge Warbler (A. schoenobaenus), Lesser Whitethroat (Sylvia curruca), Spotted Flycatcher (Muscicapa striata), and Common Redstart (Phoenicurus phoenicurus) (cf. Pyle et al. 2015), as well as at least one other long- distance vagrant that reached Gambell dur- ing the fall of 2017, River Warbler (Locustella fluviatilis) (Lehman 2018).

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