Western Birds Journal

Volume 52, No. 3

Published July 1, 2021

Issue description

Volume 52, number 3 of Western Birds, published 2021

Articles

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    JEANNE TINSMAN, MARTIN MEYERS (Author)

    NEVADA BIRD RECORDS COMMITTEE REPORT FOR 2019–2020

     In 2019 and 2020, the Nevada Bird Records Committee reviewed 79 reports from the period 4 November 1955 to 23 October 2020. Seventy of them were endorsed. It added three species to the state checklist, the Field Sparrow (Spizella pusilla), Mexican Duck (Anas diazi), and Pine Warbler (Setophaga pinus). Two of those (the Field Sparrow and Pine Warbler) were added to the review list. The Mexican Duck was elevated from subspecies to species status, and it, along with six other species, were removed from the review list. We also continued reviewing records that precede the committee’s establishment in 1994.

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    RICHARD A. ERICKSON, HORACIO DE LA CUEVA, ENRIQUE D. ZAMORA-HERNÁNDEZ (Author)

    REQUIEM FOR THE TRICOLORED BLACKBIRD IN MEXICO?

     We summarize existing literature and document a recent steep population decline and range contraction in the Tricolored Blackbird (Agelaius tricolor) at the southern end of its range, in Baja California, the only state of Mexico in which the species occurs. From >1000 nesting birds using at least 14 sites south to 30° N around the turn of the 21 st century, the population declined and contracted northward and upward in elevation to a single colony of ~150 nesting birds near the international border in 2019. Chronic drought, rising temperatures, and habitat losses due primarily to intensification of agriculture in Mexico are largely responsible for the decline, as in the core of the species’ range in California. Because of the reduction of breeding and foraging habitat, we fear the imminent extirpation of the species in Mexico.

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    DANIEL A. AIROLA, LILY A. DOUGLAS, LAYLA AIROLA (Author)

    YELLOW-BILLED MAGPIE POPULATION STATUS AND HABITAT CHARACTERISTICS IN URBAN SACRAMENTO, CALIFORNIA

     Most research on the ecology of the Yellow-billed Magpie (Pica nuttalli) has been focused in oak woodlands and savannas in California’s Coast Ranges; urban and suburban populations, some of which are sizable, have received little attention. In 2020, we studied eight colonies in six parks around Sacramento and in 2021 expanded the survey to 43 sites, detecting 827 breeding magpies. Population estimates based on nest counts were generally higher than those from direct counts, and nest counts were more repeatable and efficient. Counts of recently fledged young in family groups yielded reproductive rates similar to those observed near the coast before arrival of West Nile virus in 2003, suggesting that the virus is not currently affecting nestlings’ survival. Sacramento magpies nested in the upper canopy of a wide variety of large trees, both native and non-native. They foraged preferentially in low herbaceous habitat—irrigated turf and unirrigated annual grassland that was mowed or grazed. The presence of rivers and streams influenced occupancy strongly. Colony size was strongly related to the amount of low herbaceous foraging habitat within 0.5 km of colony sites with nearby flowing water. Our results suggest that at least 4 ha of low herbaceous foraging habitat is needed to support a small nesting colony. Retention of herbaceous habitat near large trees and flowing water, plus mowing or grazing to keep herbaceous growth low, should benefit urban Yellow-billed Magpies.

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    M. RALPH BROWNING (Author)

    TOWARD CLARIFYING THE WYOMING RANGES OF THE VIREO GILVUS COMPLEX

     The Warbling Vireo (Vireo gilvus), generally recognized as one polytypic species, is widely distributed across North America, but differences in morphology, song, genetics, and ecology suggest the western and eastern populations may represent two species. Understanding their distributions enables tracking of range changes and other factors that might affect the conservation of populations. Therefore, I studied museum specimens, specimen data, and identifications provided by investigators recording songs to help clarify the ranges of the two taxa in Wyoming. Of 18 specimens in the U.S. National Museum collected from 1858 to 1930, I identify 15 as the western species V. swainsoni. These are spread over most of Wyoming, east to Crook and Albany counties. Only three represent the eastern species V. gilvus, two from Greybull, Big Horn Co., and one from Cheyenne. Whether the overlap represents sympatry of breeding populations in eastern Wyoming or overlap in migration remains to be determined.

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    CLAIRE M. STUYCK, PAUL P. LEONARD, GERALD V. FROST, MICHELLE L. S. LAKE, JEFFREY D. WALTERS (Author)

    UPDATE ON THE STATUS AND BREEDING PHENOLOGY OF THE TIMBERLINE SPARROW (SPIZELLA BREWERI TAVERNERI) IN ALASKA

     In July 2020 we located 10 singing Timberline Sparrows [Spizella (breweri) taverneri] in the region of Gold Hill, Nutzotin Mountains, east-central Alaska. All birds were on southeast-facing slopes in the ecotone between subalpine scrub and alpine tundra, to which habitat breeding Timberline Sparrows seem narrowly confined. The population’s estimated density of 0.77 birds/km2 was similar to that at the time of its discovery in 1994. We located the first active nest of the Timberline Sparrow reported for Alaska, ~0.3 m above the ground in a shrubby resin birch (Betula glandulosa). An observation of young fledged on 11 or 12 July 2020 implies egg laying in the third week of June, later than the beginning of the
    breeding season of Spizella (breweri) breweri.

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    AARON J LANG, STEVEN C. HEINI (Author)

    FIRST RECORD OF THE PALLAS’S GRASSHOPPER WARBLER IN ALASKA

     The Pallas’s Grasshopper Warbler (Helopsaltes certhiola) is common over much of its central and eastern Palearctic breeding range, which extends from the middle Irtysh River, in western Siberia, east to the Sea of Okhotsk and south to eastern Kazakhstan, northern China, and the northern coast of the Sea of Japan in the Primorskiy region of Russia (Kennerley and Pearson 2010). It winters from Sri Lanka and eastern India east through much of southeast Asia, including Sumatra and Borneo. This species is also recorded nearly annually as a fall vagrant to northwestern Europe (ibid.), and it is an irregular visitor to Japan, where at least six fall records extend from September to November (OSJ 2012). Here we report the first record of the Pallas’s Grasshopper Warbler in Alaska

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    PAIGE C. MILLER, DAVID J. DELEHANTY (Author)

    EGG RETRIEVAL BY TRUMPETER SWANS

     The Trumpeter Swan (Cygnus buccinator), endemic to North America and its largest species of waterfowl, approached extinction in the 1930s (Banko 1960). But by 2015, following nearly a century of conservation, its population had rebounded to some 63,000 wild birds (Groves 2017). Enhanced population size has provided increased opportunity for scientific study, and previously unreported behaviors now are being observed. Here we report egg retrieval—the act of a bird moving eggs from outside the nest bowl into the nest bowl—by nesting Trumpeter Swans for the first time. Egg retrieval is an important behavior that serves to restore reproductive opportunity after disturbance at the nest.

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    CATHERINE WATERS (Author)

    BOOK REVIEW: Birds of Phoenix and Maricopa County, Arizona, Third edition

     Now that covid-19 may soon pass into our rear-view mirrors, maybe we can begin traveling again for work and pleasure. Even if we are still reticent to cross our thresholds, there is always planning our next trips, and this gem of a book is one for anyone interested in western birds. For those of us who are bound to spend time in place, this book would be a thoughtful addition to our libraries to familiarize ourselves with this wonderfully described southwest birding location.

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    KIMBALL L. GARRETT (Author)

    AN APPARENT RED-BACKED JUNCO, JUNCO HYEMALIS DORSALIS, IN CALIFORNIA

     The Dark-eyed Junco (Junco hyemalis) is a highly variable songbird found over much of North america. Winter junco flocks in California are dominated by birds of the Oregon Junco subspecies group (with J. h. thurberi being the most widespread), but small numbers of Slate-colored Juncos (J. h. hyemalis and J. h. cismontanus) and more rarely Pink-sided Juncos (J. h. mearnsi) and Gray-headed Juncos (J. h. caniceps) also occur; the White-winged Junco (J. h. aikeni) has been documented at least four times (Patten et al. 1998, Wright 2019). Different mixes of these same subspecies groups, all of which had been considered full species at times in the past, can be found in winter over much of western North america.