Western Birds Journal

Volume 56, No. 1

Published January 1, 2025

Cover image V56(1)

Issue description

Volume 56, number 1 of Western Birds, published 2025

Articles

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    ERIC A. VANDERWERF, REGINALD E. DAVID, PETER DONALDSON, RICHARD MAY, H. DOUGLAS PRATT, PETER PYLE, LANCE TANINO (Author)

    SECOND REPORT OF THE HAWAII BIRD RECORDS COMMITTEE

     This is the second report of the Hawaii Bird Records Committee (HBRC). From 2019 to 2024, the HBRC reviewed 37 reports involving 29 bird species, of which 34 reports of 26 species were accepted, two were rejected, and one required recirculation and is still under review. The accepted reports included 15 species new to the Hawaiian Islands, eight second records, one third record, and one sixth record. Two more species were added because of splits to taxa that had been recorded previously. Through 2024, the Hawaiian Islands bird checklist includes 355 species.

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    Cin-Ty Lee, Andrew Birch (Author)

    IDENTIFICATION OF WILLOW AND ALDER FLYCATCHERS BY PRIMARY-TIP SPACING: THE P6:7 RATIO.

     Discrimination of silent Alder (Empidonax alnorum) and Willow Flycatchers (E. trailli) has long been considered exceedingly difficult from photographs or under field conditions. Through extensive specimen and field research, we explored the applicability of primary-tip spacings on a folded wing to field identification. We found that the distance from the tip of primary 5 to primary 6 divided by the distance from the tip of primary 6 to primary 7, which we term the “P6:7 ratio,” is a nearly diagnostic field mark. in our sample of 217 Alder Flycatcher specimens, 95% have P6:7 < 1.02, whereas in our sample of 371 Willow Flycatcher specimens 95% have P6:7 > 1.05. Because the dividing line between the two species is close to a P6:7 ratio of 1, this field mark is discernible from photos and, with experience, in the field

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    STEPHANIE M. COBBOLD, RYAN P. O’DONNELL, MICHAEL F. INGRALDI, NORA D. CLARK, YADID LEÓN-MORENO, ANDREA GUTIÉRREZ-QUIHUIS, KAREN VERDUGO-GAXIOLA (Author)

    GRAY VIREOS WINTERING IN FRAGRANT BURSERA (BURSERA FAGAROIDES) IN CENTRAL SONORA

     The Gray Vireo (Vireo vicinior) winters primarily around the Gulf of California in coastal arid lands with high densities of the Elephant Tree (Bursera microphylla), eating a diet specialized on the fruit of this plant. We describe likely territorial behavior of the Gray Vireo at a site 112 km from the nearest coast in Sonora, Mexico, where the Fragrant Bursera (Bursera fagaroides) was the dominant Bursera species and Elephant Trees appeared to be absent. We also document the first observation of frugivory by a Gray Vireo on the fruit of Fragrant Bursera. Given that the Gray Vireo is vulnerable to habitat loss and population declines, our observations highlight the importance of investigating wintering Gray Vireos’ diet
    in areas beyond the distribution of the Elephant Tree.

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    ZACHARY M. POHLEN, JAMES A. JOHNSON, JOEL HELM (Author)

    FIRST NORTH AMERICAN RECORD OF A KENTISH PLOVER (ANARHYNCHUS ALEXANDRINUS)

     On 29 May 2023, Pohlen discovered an adult male Kentish Plover (Anarhynchus alexandrinus) at Eareckson Air Station, Shemya Island, Aleutian Islands, Alaska—a first record for North America. Features identifying the bird as a Kentish Plover and distinguishing it from the similar Snowy Plover (A. nivosus) include the rufous or tawny tinge to the crown, solidly black lores, and limited black auricular patch. The weather patterns leading up to the discovery were conducive to drift vagrancy from Asia.

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    CAMERON PIPER, KIANA ELLIOTT, NAKAILA WENGREEN (Author)

    INTERSPECIES FEEDING AND DEFENSE OF LEWIS’S WOODPECKER BY FEMALE WESTERN TANAGER

     Interspecific help caring for young is an uncommon behavior in birds. Observations of an individual of one species caring for young in the nest of another typically entail species with the same nest type. Our observation of a female Western Tanager (Piranga ludoviciana) guarding and feeding a Lewis’s Woodpecker (Melanerpes lewis) nestling adds to the meager body of observations of interspecies parental care for species with differing nest types.

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    DANIEL A. AIROLA, BOB YUTZY (Author)

    FIRST RECORD OF APPARENT HYBRIDIZATION BETWEEN THE YELLOW-BILLED AND BLACK-BILLED MAGPIES: HYBRIDIZATION

     The Yellow-billed Magpie (Pica nuttalli) and Black-billed Magpie (P. hudsonia) are closely related, but their ranges are allopatric. Both species are nonmigratory and highly sedentary, with few extralimital records. In April 2023, a Black-billed Magpie was discovered in Redding, Shasta County, California, in an area occupied by Yellow-billed Magpies. The Black-billed Magpie occurred regularly with a Yellow-billed Magpie at a bird-feeder, and subsequently two juvenile magpies with light pink and gray bills were seen together there. Because of the rarity of this bill coloration and the coincidence with a mixed-species pair, we conclude that the juveniles were the pair’s hybrid offspring. A literature review and records search
    indicate that each species occurs in the other’s range exceedingly rarely, and this appears to be the first record of presumed hybridization between the species.

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    THANK YOU TO OUR SUPPORTERS

     Western Field Ornithologists’ board of directors and Western Birds’ editorial team deeply appreciate the generosity of these many individual donors and organizations that contributed to WFO financially in 2024.