Western Birds Journal

Volume 56, No. 3

Published August 1, 2025

Issue description

Volume 56 number 3 of Western Birds, published 2025

Articles

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    NED BOHMAN, PAUL J. HURTADO (Author)

    NEVADA BIRD RECORDS COMMITTEE REPORT FOR 2021–2024

    From 2021 to 2024, the Nevada Bird Records Committee reviewed 99 reports of 57 species observed from September 2020 to June 2024, plus one earlier observation from September 1990. Of these 99, 82 were endorsed. These endorsements added five species to the Nevada state checklist: the Royal Tern (Thalasseus maximus), Wedge-rumped Storm-Petrel (Oceanodroma tethys), Hutton’s Vireo (Vireo huttoni), Nelson’s Sparrow (Ammospiza nelsoni), and Varied Bunting (Passerina versicolor). Also, the committee revised its review list, adding 31 further species to the set it considers. One species, the Mississippi Kite (Ictinia mississippiensis), was removed.

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    ERIC A. VANDERWERF (Author)

    IDENTIFICATION AND DISTRIBUTION OF THE BROWN AND COCOS BOOBIES AND THEIR SUBSPECIES

    The Brown–Cocos Booby complex occurs in tropical and subtropical oceans worldwide and consists of five named taxa. The Cocos Booby (Sula brewsteri), including the subspecies brewsteri, etesiaca, and nesiotes, was split recently from the Brown Booby (Sula leucogaster), which retains the subspecies leucogaster and plotus. Because information about their field identification is limited, especially for females, I evaluated characters distinguishing the five taxa by examining 50 museum specimens and photos of 754 living Cocos and Brown Boobies from 47 locations in the ranges of all five subspecies. The Cocos and Brown Boobies can be distinguished by at least five characters: head color, pattern of the underwing coverts, iris darkness, culmen concavity, and bill color, the importance of which differ by sex and in some cases by subspecies. The white on the head and neck of the male Cocos Booby, which varies by subspecies, is the most obvious difference from the Brown Booby. Female Cocos Boobies also have the head paler brown than in female Brown Boobies. The Cocos Booby has a darker iris and more brown in the underwing coverts. Sula leucogaster plotus has a straighter culmen and females have the bill yellow rather than pink, as in all other taxa. The extent of white on the neck of male Cocos Boobies in the Revillagigedo Islands identifies them as nesiotes rather than as brewsteri. Information about individuals that have dispersed outside the traditional range helps track their movements and in assessing effects of environmental changes on populations.

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    ANTHONY J. BRAKE (Author)

    EXPANSION OF THE BREEDING POPULATION OF THE OSPREY ON SAN FRANCISCO BAY

    The first known nesting of the Osprey (Pandion haliaetus) on San Francisco Bay was in 1990 along the Mare Island Strait in Vallejo. After 2003, the nesting population at Mare Island Strait began to grow, but nesting in San Francisco Bay south of there remained sparse. A survey in 2013 detected 26 territorial pairs about the Bay, most (65%) still concentrated along the Mare Island Strait, but a few Ospreys were found nesting to the south in Contra Costa, Alameda and San Francisco counties. Here I report the results of surveys from 2014 to 2024, which show a continued southward expansion, the greatest concentration of nests now along the Richmond shoreline in Contra Costa County, and a few nests in South San Francisco Bay. In 2024 the number of territorial pairs reached 70. The overall productivity from 2013 to 2024 of 1.40 juveniles fledged per territorial pair appears sufficient to sustain growth of the population. Of the 70 nests active in 2024, 69 were built on anthropogenic structures. In 2024, 16 of the nests were built on artificial platforms, most of which had been installed to attract Ospreys away from nesting on problematic structures such as electrical distribution poles. Effective conservation of San Francisco Bay’s urban nesting population will require installation of additional artificial nest platforms to mitigate nest removal or deterrence to protect infrastructure and prevent Osprey electrocutions.

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    GERALD J. McCHESNEY, MICHAEL A. PIERSON, MICHAEL E. JOHNS (Author)

    First record of a family group of the Ancient Murrelet in California

    A family of two adults and one half-grown chick of the Ancient Murrelet (Synthliboramphus antiquus) on the ocean at Southeast Farallon Island, California, 1 and 10 June 2019, were far south of any of the species’ known nest sites. Though Ancient Murrelets drift quickly away from their colonies once the young leave the nest at 2–3 days of age, Southeast Farallon is too far (1700 km) from Haida Gwaii for dispersal from even the southernmost known colony to be plausible. Dispersal of 1200 km from Carroll Island, Washington, a site of past and possibly current nesting, is also unlikely, suggesting the Ancient Murrelets likely nested at some yet unknown site along the coast of Oregon or northern California.

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    LANCE MORROW, JILL MORROW, STEVE COX, JASON KITTING (Author)

    WINTERING GRAY-CROWNED ROSY-FINCHES SEGREGATE LATITUDINALLY BY SEX

    Analysis of records of 8665 Gray-crowned Rosy-Finches banded over 64 years in Montana, Wyoming, Colorado, and New Mexico revealed that the sexes tend to segregate latitudinally during winter. The sex ratios of Gray-crowned Rosy-Finches banded during winter in these four Rocky Mountain states varied linearly with latitude, males predominating toward the north (male:female ratio 2.2 in Montana), females toward the south (male:female ratio 0.6 in New Mexico).

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    GERARDO MARRÓN, JONATHAN VILLARREAL, DIANA GUTIÉRREZ (Author)

    Predation of House Finch eggs by Cactus Wren

    Although the Cactus Wren (Campylorhynchus brunneicapillus), like some other wrens, is well known for destroying other birds’ eggs, it has not been reported eating those eggs. We observed an incident of a Cactus Wren consuming the contents of an egg it took from a House Finch (Haemorhous mexicanus) nest ~25 km southeast of La Paz, Baja California Sur, Mexico.

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    OSIEL FLORES, GERARDO MARRÓN (Author)

    A NEST OF THE CAPE PYGMY-OWL (GLAUCIDIUM GNOMA HOSKINSII)

    No nest of the Cape Pygmy-Owl (Glaucidium gnoma hoskinsii) has been reported previously. Therefore, it is of value to put on record the observation of a nest in a cavity in a Mexican fan palm (Washingtonia robusta) at an elevation of 360 m near the east base of the Sierra de la Laguna in the cape region of Baja California Sur, Mexico. The nest had at least one young near fledging on 28 May 2023. Prey carried to the nestlings included small lizards.

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    ROBERT L. PITMAN, RICHARD A. ERICKSON, CHRISTOPHER HOEFER, DAWN BREESE (Author)

    A MOTTLED PETREL IN THE NORTHERN GULF OF CALIFORNIA—MEXICO’S FIRST RECORD

    A Mottled Petrel (Pterodroma inexpectata) seen and photographed at a distance off San Felipe in the Gulf of California on 15 May 2024 represents a first of its species to be noted in Mexico. On its passage north the Mottled Petrel, a transequatorial migrant, crosses the central Pacific mainly in March and April, suggesting that the bird seen off San Felipe in May could have been trapped and delayed in the Gulf of California while heading north, albeit far to the east of its normal route.

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    DAVID KOEPPEL (Author)

    Book Review: National Geographic Field Guide to the Birds of the United States and Canada—West, National Geographic Field Guide to the Birds of the United States and Canada—East

    The release of The National Geographic Field Guide to the Birds of the United States and Canada, Eighth Edition affirms a pleasing paradox. In a digital age when identification aids, distribution data, and taxonomic relationships are, quite literally, at one’s fingertips, the demand for hard-copy books on birds has never been greater.

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    DANIEL A. AIROLA (Author)

    IN MEMORIAM: Edward C. (Ted) Beedy, 1950–2025

    Edward C. Beedy, a >40-year WFO member, passed away suddenly on 28 March 2025 at the age of 75. Ted, as he was universally known, was a highly respected, dedicated, and visionary wildlife biologist, ornithologist, environmental consultant, conservationist, and birder who lived nearly his whole life in northern California.