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.

Issue link: http://nab.aba.org/i/629070

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a b a b a c d c d c c d c d c 25 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 Specimen examination by Pyle of males with basic or formative primaries indicated that in Red-backed Shrikes white bases were absent in 50% and extended beyond the primary coverts in 8.3% of specimens (n=36), while in cristatus Brown Shrikes white was absent in 72% and extended be - yond the primary coverts in no specimens (n=18); similar results were found among 21 male lucionensis specimens and among 41 cristatus Brown Shrikes of other ages the primary coverts is also very rare in nominate cristatus Brown Shrikes (Svensson 1992, Cramp and Perrins 1993, Worfolk 2000, Panov et al. 2011). Although exten - sive white bases in the primaries appear to be shown by a larger proportion of confusus Brown Shrikes (Moores 2004, 2015), this subspecies is unlikely part of a hybrid com - bination with Red-backed Shrike due to the distantly discrete breeding ranges of these two taxa (Figure 4). It has been widely documented that white extending beyond the primary coverts oc - curs only occasionally in Red-backed Shrike, in 8-9% of individuals according to Glutz von Blotzheim and Bauer (1993, in Panov et al. 2011); Chylarecki (1991) and Panov et al. (2011) further suggest that an appar - ent increase in extent of the white primary patch toward eastern portions of the breed - ing range may relate to introgression with Turkestan Shrike. White extending beyond Figure 15. Distances between the tips of primaries and primary coverts (a; 3 April), and between rectrices (b, c; 27 and 30 March, respectively) in order to calculate wing and tail morphology ratios of the Mendocino shrike for identifcation. The distances are between the tips of p8 and p9 (a), between the tips of p9 and the primary coverts (b), between the tips of r5 and r6 (c), and the estimat- ed total length of r6 from point of insertion to tip (d). Ratios a/b and c/d from juvenile feathers were calculated from photographs and compared to the same measures taken on specimens (Table 1b). For example, ratios from these images are a/b = 0.115 (a), c/d = 0.132 (b), and c/d = 0.102 (c); see Table 1b. Photographs by Don Roberson (a), John Sterling (b), and Monte Taylor (c). 15a 15b 15c

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