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

Contents of this Issue

Navigation

Page 7 of 179

6 N O R T H A M E R I C A N B I R D S T H E M E N D O C I N O S H R I K E song with those of the taxa in this assem- blage. Although uncertainty is unavoidable when attempting to identify hybrids, we believe that plumage features, along with perhaps more telling wing and tail struc - tural morphologies, point to Red-backed x Turkestan Shrike hybrid as the identifca - tion of the Mendocino bird. We also con- sider how such a hybrid, from a limited breeding area that extends from the Cas - pian Sea to the Altai region of south-central Russia, might reach California via reverse migration (180º misorientation). Field encounter and description On 5 March 2015, Alison Cebula and Rob- ert Kunicki, interns with California State Parks, were conducting a shorebird survey near the mouth of Alder Creek, Manches - ter Beach State Park, Mendocino County, California, when they spotted what they tentatively identifed as a Northern Shrike (Lanius excubitor). Cebula obtained a di - giscoped image (Figure 1a) and sent it to Richard Hubacek, who believed it more likely a Brown Shrike (L. cristatus), a rare vagrant to California. Keiffer received the image on 9 March, agreed that the bird resembled a Brown Shrike, and forward - ed it to Dunn and Pyle. Both Dunn and Pyle concurred that it was not a Northern Shrike and was probably a Brown Shrike, although both were puzzled by the grayish wash to the crown, Dunn supposing that it might be of the southeastern subspecies of Brown Shrike (L. c. lucionenesis) and Pyle wondering if a duller Red-backed Shrike (L. collurio) could be eliminated. The shrike proved somewhat elusive, disappearing for hours and up to fve days at a time, but numerous observers got to see and photograph it over the ensuing six weeks, usually at some distance. It spent most of its time along a brushy ridge bor - dering open grasslands, on private prop- erty across the creek. It was last observed and photographed on 22 April by Murray Brown of British Columbia (Figure 1b), after an absence of observations since 17 April and a general presumption that it had already migrated north. Keiffer observed it on 14 March, Dunn on 24 March, and Pyle on 1 April. During the period of observa - tion, the shrike was undergoing molt of fight feathers and body feathers, resulting in a shifting appearance that elicited shift - ing opinion as to its age and identity. It was also heard singing, and two recordings by Steve Hampton were posted to xeno-canto (www.xeno-canto.org) under "identity un - known." The bird was widely thought to be a Brown Shrike during the frst two weeks of observation. Not convinced of this, Pyle sent images to Moores, who has ex - tensive experience with Asian shrikes and their identifcation in Korea, where Brown Shrike is a locally common migrant and uncommon breeder (Moores 2004, 2015). Moores's frst reaction was that many fea - tures were at odds with a pure Brown Shrike, that it did not show indisputable features of any species or subspecies, and that it seemed most likely a dull eastern Red-backed Shrike or perhaps a hybrid between a Red-backed Shrike and either a Turkestan (L. phoenicuroides) or Isabelline (L. isabellinus) Shrike—three species previ - ously unrecorded in North America. Interest in the shrike increased substan- tially after internet discussion turned to- ward Red-backed Shrike and hybrids. Kei- ffer contacted observers of the bird to obtain documentary photographs, especially those showing spread wing and tail for analysis of molt, age, and identifcation. With each new series of posted images, as the bird continued to molt (Figures 1-3), came new rounds of discussion as to its identifca - tion, including comments from those famil- iar with this shrike assemblage in Europe and Asia. Complicating these discussions, digital images (captured with many types of cameras) displayed variable levels of red saturation in the back color (Figure 2). Ob - servers anticipated a secure identifcation once the shrike had completed its molt, but, unfortunately, this did not occur before the bird was last photographed. By mid-April, Figure 2. The upperparts of the Mendocino shrike during diferent dates and showing diferent efects of lighting and variable levels of red saturation: 19 March (a), 27 March (b), 30 March (c), 1 April (d), 6 April (e), and 16 April (f ). Careful comparison of feld descriptions with these images indicate that images b and c come closest to representing the shrike's actual back coloration, which we describe as rufous-brown. Photographs by Joe Morlan (a), John Sterling (b), Monte Taylor (c), Larry Sansone (d), Barrett Pierce (e), and Mark Rauzon (f ). 2a 2b

Articles in this issue

Links on this page

Archives of this issue

view archives of North American Birds - VOLUME 69 No1 2016