Western Birds Journal

Volume 54, No. 1

Published January 1, 2023

Issue description

Volume 54, number 1 of Western Birds, published 2023

Articles

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    XERÓNIMO CASTAÑEDA, NEIL CLIPPERTON, DANIEL A. AIROLA, SAMANTHA ARTHUR, PAUL SOUSA (Author)

    EFFECTIVENESS OF PUBLIC–PRIVATE EFFORTS TO CONSERVE TRICOLORED BLACKBIRD COLONIES ON AGRICULTURAL LANDS IN THE SAN JOAQUIN VALLEY, CALIFORNIA

     Since the early 1990s when much of the population of the Tricolored Blackbird (Agelaius tricolor) began nesting in fields of triticale grown for dairy silage in the San Joaquin Valley, many colonies have been destroyed inadvertently during harvest. After previous inconsistent efforts, in 2015 a Regional Conservation Partnership Program brought the dairy industry, Natural Resource Conservation Service, Audubon California, California Department of Fish and Wildlife, and other partners together in an effort to stem the losses. The program located colonies and compensated farmers for crop value lost when the harvest was delayed until after the blackbirds fledged and encouraged creation of alternative nesting habitat to attract nesting birds away from agricultural fields. Before 2015, data on the numbers of colonies in silage fields, and on the blackbirds’ productivity conserved and lost, are complete only for 2005–2009, when only 43% of colonies encompassing 60% of the monitored nestings avoided destruction. From 2015 to 2022, 93% of colonies representing 96% of nesting attempts were conserved, and the number of birds nesting in silage increased by as much as 100,000. The program’s success resulted from the adequacy of federal funding, protection provided by the species’ listing as endangered by the state of California, and effective communications and cooperation among the partners and within the dairy industry. Protection of colonies in silage fields since 2015 likely contributed to the substantial increase in the numbers of birds nesting in this habitat and perhaps to an increase in California’s Tricolored Blackbird population as a whole. Continued effort is needed to achieve the species’ recovery.

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    DANIEL A. AIROLA, TARA L. COLLINS, CHRISTOPHER J. McCOLL, MICHAEL R. LOZANO, BRETT J. FURNAS, DAVID E. KROLICK (Author)

    FORAGING HABITAT AND ITS EFFECTS ON THE TRICOLORED BLACKBIRD’S BREEDING DISTRIBUTION AND ABUNDANCE IN THE SIERRA NEVADA FOOTHILLS, CALIFORNIA

     The grassland-dominated eastern Central Valley and Sierra Nevada foothills of California, from Placer to Stanislaus counties, supported at least 43,000–55,000 breeding Tricolored Blackbirds (Agelaius tricolor) annually from 2014 to 2018—about 30% of the statewide population. We found that within 5 km of a colony, the extent of land cover used for foraging, grassland–herbaceous, and to a lesser extent annual crops and irrigated pasture, exceeded their proportions in this region as a whole, suggesting that nesting Tricolored Blackbirds select colony sites where these habitats are more abundant. Other land-cover types were underutilized for foraging, suggesting avoidance. The probability of Tricolored Blackbird occupancy of blocks of 100 km2 was strongly associated with the extent of the selected land-cover types. The relationship between average density of the breeding population and the extent of the selected land-cover types was significant but weaker, implying that other factors are important in determining density. From 2014 to 2018, development and mining eliminated or degraded 9 of 79 colony sites and made 4 others unsuitable by reducing the extent of nearby foraging habitat, although the total breeding population in the region did not decline. We recommend that conservation measures for the Tricolored Blackbird in federally and state-approved habitatconservation plans in Placer and Sacramento counties, which support the largest breeding populations in the central Sierra foothills but where urban development is rapid, be reevaluated on the basis of recent colony locations and recognition of the critical role of grassland, annual crops, and irrigated pasture as foraging habitat.

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    PETER H. BLOOM, RAINEY G. BARTON, MICHAEL J. KUEHN (Author)

    SWAINSON’S HAWK NESTING POPULATION IN THE ANTELOPE VALLEY OF THE WESTERN MOJAVE DESERT, CALIFORNIA

    The Swainson’s Hawk (Buteo swainsoni) has a long history of breeding in california, but a severe decline in the statewide breeding population was identified in 1979, when in all of southern california only two pairs were found, one in the antelope Valley of the western mojave Desert. that area was little studied until we began banding Swainson’s Hawks there in 1997. over 20 breeding seasons between 1979 and 2022, we documented in the antelope Valley 124 attempts to nest, in which the mean clutch and brood sizes were 2.49 and 2.37, respectively. From 2004 through 2006, we observed two to four breeding pairs annually; from 2009 through 2022, three to 14 breeding pairs. the rate of success of the 91 nests revisited to determine if any young fledged was 64%. nest trees consisted of 81.5% non-native species, 13.7% native species, including Joshua trees (Yucca brevifolia), and 4.8% unidentified deciduous trees. Between 1997 and 2022, in 50 nests, we recorded 170 vertebrate prey items, of which 90 were gophers (Thomomys bottae). though the antelope Valley population has grown since 1980, its nesting and foraging habitat now face multiple threats. to conserve occupied nesting territories, we recommend creation of nesting and foraging habitat reserves that include both native desert and cultivated alfalfa close to existing conserved land.

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    THOMAS P RYAN, STACEY VIGALLON , ROSS GRISWOLD, LUCIEN PLAUZOLES, CHERYL EGGER, SUSAN SHEAKLEY, LANA NGUYEN , ROBERT SCHALLMANN (Author)

    STATUS OF THE WESTERN SNOWY PLOVER IN COASTAL LOS ANGELES AND ORANGE COUNTIES, CALIFORNIA

    From 2004 to 2021 we monitored the Western Snowy Plover (Charadrius nivosus nivosus) in coastal Los Angeles and Orange counties, California. Following an absence of 68 years, it returned to nest in 2017. Since then, the plovers have nested at three locations in Los Angeles County and four in Orange County, where numbers of nests at Anaheim Bay, Bolsa Chica State Beach, and Huntington State Beach increased. Protective beach management and nest enclosures presumably contributed to the increase of nests and hatching success at these sites. However, the number of nonbreeding Snowy Plovers in coastal Los Angeles County has declined, most steeply at Zuma Beach. At nonbreeding roosts in Orange County, numbers at Balboa Beach and San Onofre State Beach declined, but countywide numbers were stable. All sites at which plovers roost experience human-related disturbance, which may include vehicles driving through them regularly, beach grooming that removes wrack and foraging resources, dogs chasing and flushing roosting plovers, and nearby large recreational events and summer camps as nonbreeding plovers return in July. Most sites lack consistent protective measures. Plover mortality has resulted from vehicle strikes and dogs. We recommend management that includes the establishment of special protection zones, restrictions on sand grooming, wrack removal, and vehicle traffic, and installation of protective enclosures around roost sites.

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    JACK J. WITHROW (Author)

    EURASIAN WIGEON BREED IN THE ALEUTIAN ISLANDS, ALASKA

     In June 2022, while collecting in the Aleutian Islands, Alaska, for the University of Alaska Museum, I observed at least three broods of Eurasian Wigeon (Mareca penelope) on Amchitka Island (51.39° N, 179.26° E) and two broods on Adak Island (51.92° N, 176.64° W). So far as I have been able to determine the specimens collected from them represent the first actual documentation of nesting by the species in North America.

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    DARRELL L. WHITWORTH, MICHAEL W. PARKER, JAMES A. HOWARD, DAVID M. MAZURKIEWICZ, HARRY R. CARTER (Author)

    BREEDING OF THE GUADALUPE MURRELET IN SOUTHERN CALIFORNIA

     After having been observed regularly at Seal Cove, San Clemente Island, California, since 1994, the Guadalupe Murrelet (Synthliboramphus hypoleucus) was confirmed nesting successfully in an artificial nest on a rocky ledge above the cove in 2022. The incubating adults’ identity and the two chicks’ departure from the nest were confirmed by a trail camera. Another Guadalupe Murrelet nest at Santa Barbara Island in 2021 was only the second confirmed there. Though the populations of the Guadalupe Murrelet at San Clemente and Santa Barbara islands are apparently small, they are important in representing the only confirmed sites of the species’ nesting away from Guadalupe and the San Benito islands.

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    MATTHEW J. BAUMANN (Author)

    THE FIRST TROPICAL KINGBIRD NEST IN NEW MEXICO

     A nest of the Tropical Kingbird (Tyrannus melancholicus) at Sumner Lake State Park, De Baca County, 17 June 2022, was the first found in New Mexico. It followed summer sightings elsewhere in southern New Mexico since 2010 and is part of a pattern of northward spread of the species’ breeding range in Arizona and Texas.

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    GORGONIO RUIZ-CAMPOS, GONZALO DE LEÓN-GIRÓN, TONATIUH GAONA-MELO, GERARDO MARRÓN, PHILIP UNITT, LORI HARGROVE (Author)

    THE NORTHERNMOST RECORD OF THE LEAST GREBE (TACHYBAPTUS DOMINICUS BANGSI) IN BAJA CALIFORNIA

     A specimen of the least Grebe (Tachybaptus dominicus bangsi) from San Francisco de la Sierra, Baja California Sur, mexico, collected 6 april 2022, was 36 km north of the oasis of San ignacio, where the species breeds and site of the previous northernmost records on the peninsula. The bird’s occurrence on a small isolated pond yet coming into breeding condition highlight the species’ opportunism, possibly critical to its survival on the arid Baja California peninsula where freshwater oases suitable for the least Grebe are few.

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    Christopher W Swarth (Author)

    BOOK REVIEW: ROGUE BIRDER: THE MAKING OF A MODERN ORNITHOLOGIST

     This freewheeling, readable memoir describes youthful passion, a deep affection for a rural, wild place and its birdlife, and the early formative experiences that led the author to eventually migrate from Oregon to a career with the Biological Survey at the U.S. National Museum. The book’s title hints at a double meaning, which is its intent: “A Rogue Birder birds the Rogue River watershed. A Rogue Birder is also a state of mind, an attitude.” The author perceives himself, and rightly so, as a gentle gadfly who enjoys challenging the conclusions about the taxonomy and distribution of Oregon birds. The natural setting is the vast and diverse Rogue River Valley of southwestern Oregon. The climate and vegetation here “bridged the gap between environments of the Coast Range and east to the Great Basin.” In the 1950s, when this tale begins, this region’s birdlife was little explored. Over the decades, Browning made it a life’s goal to fill in the blanks by documenting range extensions and new records. As a result, “Rogue Birder” teaches a lot about the distributional limits of birds in southern Oregon. The book is organized into 16 chapters which carry us on a meandering path that reveals the many early field adventures that led to deeper thinking about bird biology and science. While it follows a general chronology, the chapters do no not have to be read sequentially for the memoir to be appreciated. Browning makes passing mention of his scientific papers, but the reader could have appreciated his many contributions more fully if a bibliography of his publications had been included.

     

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    THANK YOU TO OUR SUPPORTERS

     Western Field Ornithologists’ board of directors and Western Birds’ editorial team give thanks to these many individual donors and organizations that contributed to WFO financially in 2022. In particular, we thank Ron Mallory, whose challenge was met by these contributors. As a result, our financial health remains strong.

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    WFO NEWS

     Looking Back on 2022, Anticipating the Coming Year
    WFO President John Harris summarizes the achievements of the past year, previews upcoming programs for 2023, and discusses the financial status of the organization: https://westernfieldornithologists.org/looking-back-on-2022-lookingahead-to-2023/.