Western Birds Journal

Volume 52, No. 4

Published October 1, 2021

Issue description

Volume 52, number 4 of Western Birds, published 2021

Articles

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    DEBORAH J. HOUSE (Author)

    FALL WATERFOWL USE OF BRIDGEPORT RESERVOIR, MONO COUNTY, CALIFORNIA

     Aerial surveys from 2003 to 2019 documented the abundance of waterfowl at Bridgeport reservoir in Mono County, California, from september through mid-November. Waterfowl totals at Bridgeport reservoir averaged 33,106 ± 4050 (standard error) in the fall. annual peak counts averaged 10,474 ± 1349, ranging from a low of 2583 in 2014 to the highest single-day count of 23,150 in 2005. Bridgeport reservoir is a man-made water body in the intermountain West that waterfowl use primarily a mid-migration stopover site, with peak numbers occurring in september. The dominant waterfowl species, the Northern shoveler (Spatula clypeata), Gadwall (Mareca strepera), Mallard (Anas platyrhynchos), Northern Pintail (A. acuta), and Green-winged Teal (A. crecca), showed both unimodal and bimodal migration chronologies. regional drought, as indicated by the Palmer drought severity index, combined with a downward trend in waterfowl numbers explained 61.4% of annual variation in fall waterfowl totals. These data may allow future assessment of change in waterfowl abundance at Bridgeport reservoir in the context of local or regional conditions, and as influenced by climate change.

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    CAROLYN A. COOK, GLEN T. HVENEGAARD, GEOFFREY L. HOLROYD, HARDY PLETZ, MYRNA PEARMAN (Author)

    AGE AND SEX INFLUENCE NATAL AND BREEDING DISPERSAL OF PURPLE MARTINS

     Dispersal patterns deepen our understanding of population dynamics. Dispersal by all age and sex classes enhances a species’ ability to respond to environmental changes, such as in habitat availability, artificial nest sites, and climate. The migration dynamics of the eastern subspecies of the Purple Martin (Progne subis subis) are well known, but we know less about its patterns of annual dispersal. We compared the frequency, distance, and direction of dispersal by each age/sex cohort of martins in central Alberta, at the northwestern limit of their breeding range. We used two datasets: (1) adult martins banded in central Alberta as nestlings and encountered during the summers of 2017 and 2018, and (2) records of encounters of banded martins in Canada from 1935 to 2016 from the Canadian Wildlife Service’s Bird Banding Office. In Alberta, 36% of birds dispersed from natal sites (by an average distance of 24 km), most commonly to the northeast. Across Canada, 29% of birds dispersed (by an average distance of 183 km), most commonly to the east and northeast. In
    Alberta, martins at least two years old dispersed less frequently than yearlings since some older martins returned to their natal site after first breeding elsewhere. Dispersal distances of after-second-year martins, which represent natal plus breeding dispersal, were greater than those of second-year birds, which represent natal dispersal alone. Thus some martins continue to disperse after their second year and do not maintain complete fidelity to a breeding site, which is different from our current understanding

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    EDWARD R. PANDOLFINO, LILY A. DOUGLAS (Author)

    USING SONG DIALECTS TO ASSESS THE MIGRATION STRATEGY OF THE GOLDEN-CROWNED SPARROW

     Most techniques used to study migration of wild birds require capture for banding or for attachment and/or recovery of tags or transmitters. We took advantage of the fact that the Golden-crowned Sparrow (Zonotrichia atricapilla) sings in winter, combined with published data on the distribution of its distinct song dialects in the breeding range, to assess its migration strategy and migratory connectivity by means of these dialects. Using recordings of the Golden-crowned Sparrow’s song across much of its winter range, we categorized these birds by song type to identify their likely origin in some subset of the breeding range. This method allows examination of migration without the need to capture birds. Our results fit best with a pattern of chain migration, with the northernmost breeders wintering in the northernmost part of the winter range, and the southerly breeders wintering farther south. The results suggest strong migratory connectivity between segments of the breeding and winter ranges, though our small sample size makes it difficult to draw firm conclusions on connectivity.

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    RYAN S. TERRILL, CHRISTINE A. DEAN, JOHN GARRETT, DANIEL J. MAXWELL, LAUREN HILL, ANDREW FARNSWORTH, ADRIAAN M. DOKTER, MORGAN W. TINGLEY (Author)

    A NOVEL LOCALITY FOR THE OBSERVATION OF THOUSANDS OF PASSERINE BIRDS DURING SPRING MIGRATION IN LOS ANGELES COUNTY, CALIFORNIA

     Avian migration is a spectacular phenomenon, representing the annual movements of billions of birds globally. Because the greatest diversity and numbers of birds migrate at night, opportunities to observe active migration are rare. At a number of localities in North America, however, observers can quantify movements of many typically nocturnal migrants during daylight where they continue after dawn. Such locations have provided much information about species-specific phenology, status, and orientation during migration. Localities where morning flights of land birds can be observed are unevenly distributed, however, and are little reported along the Pacific coast. Here we describe a novel location for the observation of spectacular morning flights of nocturnal migrants during spring migration at Bear Divide, in the western San Gabriel Mountains, Los Angeles County, California. In two years of informal surveys at the site, we have recorded at least one morning with an estimated ~13,500 individual birds passing. Our preliminary analyses suggest that the peak of a species’ migration at Bear Divide is correlated with the latitude of a species’ breeding, being later in the spring as that latitude increases. Our data from Bear Divide provide an independent perspective on migration as quantified by local radar. Further work at this locality may help inform our knowledge of migration phenology and population trends.

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    PHILIP G. HIGGINS, DEBRA CHROMCZAK, RYAN A. PHILLIPS (Author)

    BURROWING OWLS PRODUCE SECOND BROOD IN MOUNTAIN VIEW, CALIFORNIA

     Western Burrowing Owls (Athene cunicularia hypugaea) are capable of laying up to 12 eggs in a single clutch (Haug et al. 1993). If the first nest attempted in a season fails, the female often lays a replacement clutch (Thomsen 1971, Wedgewood 1976). But rearing of a second brood after the fledging of a first brood (double brooding) is uncommon in this species (Millsap and Bear 1990, Gervais and Rosenberg 1999). In 2020, after 23 years of continuous monitoring of Burrowing Owls nesting around the southern periphery of San Francisco Bay at Shoreline Regional Wildlife Area in Mountain View, Santa Clara County, California, we confirmed double brooding for the first time. The Burrowing Owls were being supplementally fed with mice to assess whether such feeding during the breeding season increases their reproductive success; this experiment may have resulted in the double brood. However, this instance of double brooding occurred three years after supplemental feeding commenced.

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    HIRAM RAFAEL MORENO-HIGAREDA, GORGONIO RUIZ-CAMPOS, MANUEL ALEJANDRO CARBALLO AMADOR, HORACIO DE LA CUEVA (Author)

    CHARACTERISTICS OF NESTS OF BELDING’S SAVANNAH SPARROW AT ESTERO PUNTA BANDA, MÉXICO

     Belding’s Sparrow (Passerculus sandwichensis beldingi) is one of the 17 currently  recognized subspecies of the Savannah Sparrow (Wheelwright and Rising 2008). It can be found in saltmarshes from Point Conception, California, to the estuary of Arroyo El Rosario, Baja California (Van Denburgh 1924, Zembal et al. 1988, Wheelwright and Rising 2008) and since 1974 has been designated as endangered by the California Department of Fish and Wildlife. Bradley (1994) suggested that this subspecies is largely isolated, with a low capability for dispersal, and Powell and Collier (1998) found no movement in or out of a marsh on San Diego Bay isolated by only 0.5 km from the next nearest marsh.

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    HUGO GONZÁLEZ-PÁEZ, ARMANDO J. CONTRERAS-BALDERAS, GORGONIO RUIZ-CAMPOS, JUAN A. GARCíA-SALAS (Author)

    FIRST RECORD OF THE LONG-TAILED DUCK FOR COAHUILA, MEXICO

     The Long-tailed Duck (Clangula hyemalis) is a distinctive sea duck that breeds on high arctic coasts and tundra of both the eastern and western hemispheres. In North America, it winters south along the Pacific coast to California and along the Atlantic coast to northern Florida. In the interior of the continent, it winters regularly in large numbers on the Great Lakes (AOU 1998, Robertson and Savard 2002). The species occurs in migration or winter in all states of the continental U.S., including south to the Gulf of Mexico from Florida to Texas, and across the interior of the border states of Texas, New Mexico, Arizona, and California, where rare but annual in occurrence (AOU 1998, https://eBird.org).

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    ZACHARY M. POHLEN, CALLIE F. GESMUNDO, NICHOLAS R. HAJDUKOVICH (Author)

    FIRST DOCUMENTED BREEDING OF THE BLACK-HEADED GROSBEAK IN ALASKA

     The Black-headed Grosbeak (Pheucticus melanocephalus) breeds regularly across much of western North America from Oaxaca north to southern British Columbia and from the Pacific coast to central Nebraska (Ortega and Hill 2010). The northern limit of the species’ range has expanded steadily in British Columbia since the 1940s (Campbell et al. 2001, Martell 2015). Here we report the first documented instance of the Black-headed Grosbeak breeding in Alaska.

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    EDWARD R. PANDOLFINO (Author)

    BOOK REVIEW: Birdpedia: A Brief Compendium of Avian Lore

     Having spent parts of my life in the worlds of academic biochemistry, the medical device business, and ornithology, I know only too well how much those who dwell in these fields love to use jargon. In some cases, the jargon provides a more succinct way to describe an observation (it is easier to say that the Common Nighthawk is largely crepuscular than to say it is most active in the twilight of evening and early morning). On the other hand, if you saw a Bald Eagle steal a fish from an Osprey, you are just showing off if you insist, in polite conversation, on saying that the eagle kleptoparasitized the Osprey. Use of such terms can create a barrier to those just getting interested in birds and ornithology. Leahy’s earlier tomes, The Birdwatcher’s Companion (1982) and The Birdwatcher’s Companion to North American Birdlife (2004), provided a source for those of all levels of interest to translate our ornithological jargon into plain English. These books also provided a fairly exhaustive treatment of many aspects of the field, including the history and personalities that shaped ornithology in North America. In many ways, one can consider Birdpedia a “sampler” from those larger books. Indeed, in his preface Leahy refers to this book as a “teaser,” with the intent to turn a “nagging curiosity into a compelling fascination … with the natural world.” In this sense, the target reader is likely someone who birds and is becoming more interested in understanding the world of birds more broadly and deeply