Western Birds Journal

Volume 51, No. 4

Published October 1, 2020

Issue description

Volume 51, number 4 of Western Birds, published 2020

Articles

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    W. DAVID SHUFORD, KATHY C. MOLINA, JOHN P. KELLY, T. EMIKO CONDESO, CONDESO COOPER, DENNIS JONGSOMJIT (Author)

    DISTRIBUTION AND ABUNDANCE OF DOUBLECRESTED CORMORANTS NESTING IN THE INTERIOR OF CALIFORNIA, 2009–2012*

     As part of an 11-state inventory, we censused the Double-crested Cormorant (Phalacrocorax auritus) in the interior of California from 2009 to 2012, using a combination of aerial, ground, and boat surveys. An estimated 8791 pairs breeding in the interior of the state in 2009–2012 exceeded the 7170 pairs estimated in 1998–1999. In both periods, cormorants were breeding in 9 of 11 ecoregions, but three-fourths were at one site—Mullet Island at the Salton Sea in the Sonoran Desert ecoregion (abandoned in 2014). Th ecoregions with the next highest proportions were the Sacramento Valley, San Joaquin Valley, and Modoc Plateau. Th apparent increase in numbers and colony sites since 1999—consistent with the pattern through much of western North America—reflcts the (short-lived) increase in numbers at the Salton Sea, an increasing number of colonies and breeding pairs in the Central
    Valley, and slightly better coverage on the recent surveys. Because of practical survey constraints and limited data to date, evidence of change in numbers of Double-crested Cormorants breeding in the interior of California between 1998–1999 and 2009–2012 is inconclusive. Plans for monitoring will need to take into account the effcts of substantial annual variation in numbers, which may be associated with large flctuations in cormorants’ prey base, short-term cycles of drought and flod, shift of nesting cormorants into or out of the interior of California, and the expectation of greater environmental flctuations with continuing climate change. Th factors most likely to limit the number of cormorants breeding in the interior of the  state are habitat loss or alteration (particularly from reallocation of water for human
    needs), disease, human disturbance, and the long-term effcts of climate change.

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    EDWARD R. PANDOLFINO, CHRIS RAY (Author)

    COMPARISON OF THE SONGS OF CASSIN’S AND PLUMBEOUS VIREOS

     We compared the songs of Cassin’s (Vireo cassinii) and Plumbeous (V. plumbeus) Vireos to determine if there are characteristics that could allow one to confiently distinguish between these species by song. Using recordings made in the breeding season and within the undisputed breeding ranges of each species, away from the zone of contact, we compared fie characteristics of a song: phrase length, rate of phrase delivery, proportion of frequency-modulated (buzzy) phrases, proportion of doubled phrases, and midpoint frequency between the highest and lowest frequencies of a phrase. among these, the only character in which the species diffred signifiantly was the average midpoint frequency of song phrases. despite overlap between the species in the distribution of average midpoint frequency, a criterion of 3215 hz allowed ~84% of the vireo songs in our sample to be identifid correctly. We also tabulated expected proportions of true and false positive species identifiations based on the full range of average midpoint frequencies likely to be encountered, fiding that values >3410 hz have a >95% probability of representing Cassin’s Vireo, and values <3050 have a >95% probability of representing the Plumbeous Vireo. Various fild guides show conflcting breeding ranges for these species, and there are many fild reports of both vireos outside their known breeding ranges in the breeding season. Given that visual identifiation of these birds in the fild can be diffilt when individuals are in faded spring/summer plumage, song may allow us to better defie the actual limits of these species’ breeding ranges.

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    RALPH V. PERICOLI, EMMA L. KARSTEN, ALLEN M. FISH, CHRISTOPHER W. BRIGGS (Author)

    NESTING BIOLOGY OF URBAN COOPER’S HAWKS IN ALAMEDA COUNTY, CALIFORNIA

     In recent decades Cooper’s Hawks have successfully colonized urban landscapes, where there may be ample prey but also a greater prevalence of disease in their prey. We searched for nesting Cooper’s Hawks in and around Berkeley, California, from 2002 to 2010, locating 95 nests, 89 of which successfully fldged at least one nestling. On average, each nest produced 3.6 fldglings. We evaluated the possible effcts of the protozoan parasite Trichomonas gallinae on Cooper’s Hawk reproduction from the proportion of potential prey items brought to Lindsay Wildlife Experience that tested positive for the parasitic disease. We did not fid a correlation between T. gallinae in potential prey species and nest success (i.e., if the nest fldged any offpring) or reproductive success (i.e., number of fldglings produced). Similarly, we did not fid a relationship between reproductive success and distance to parks or percent of impervious surface within 500 m of the nest. The high reported rates of reproduction and high densities of Cooper’s Hawk in Berkeley and neighboring Albany suggest a robust population, and we did not fid evidence that T. gallinae inflences its reproductive success.

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    KENNETH P. ABLE (Author)

    FIRST EVIDENCE OF BREEDING OF THE RED-NECKED GREBE IN CALIFORNIA

     On 13 September 2019, I observed an adult Red-necked Grebe (Podiceps grisegena) accompanying two large young in juvenal plumage (Figure 1) near the boat-launch site on Big Lake, ~6 km north of McArthur, Shasta County, California. Covering ~3 km2, Big Lake is a relatively shallow (~4 m deep) spring-fed lake at an elevation of 1008 m. With other connected water bodies (Horr Pond, Tule, Little Tule, and Fall rivers), it is part of a large hydroelectric project constructed in the early decades of the 20th century. Th lake and several small islands are surrounded by a dense band of emergent aquatic vegetation, primarily tule (Schoenoplectus acutus). Pied-billed (Podilymbus podiceps), Eared (Podiceps nigricollis), Western (Aechmophorus occidentalis), and a few Clark’s (A. clarkii) Grebes nest on the lake.

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    EMILIE STRAUSS, DAVID L. SWANSON (Author)

    APPARENT USE OF A ROCK CREVICE AS A NOCTURNAL ROOST BY A RUBY-CROWNED KINGLET

     relatively little is known about the locations of North american landbirds’ winter roosts (Skutch 1989, Dobbs and martin 2000). North american Piciformes and cavity-nesting passerines have frequently been documented using cavities and variations thereof for overnight roosts during the non-nesting season, but relatively little is known about where passerines that nest in cups or other open structures spend the night (Skutch 1989, Dobbs and martin 2000, antczak 2010). Th rubycrowned Kinglet (Regulus calendula), an insectivorous cup-nesting species, has not been observed either nesting or roosting in cavities (Swanson et al. 2008). it breeds in coniferous forests in Canada, alaska, northern New England, and the western united States, and winters across western, mid-central, and southern North america south through mexico to Guatemala. in central California, the ruby-crowned Kinglet winters commonly (lepthien and Bock 1976, Swanson et al. 2008).

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    GORGONIO RUIZ-CAMPOS, GONZALO DE LEÓN-GIRÓN, HIRAM RAFAEL MORENO-HIGAREDA, ARMANDO JESÚS CONTRERAS-BALDERAS (Author)

    UNUSUAL RECORD OF BONAPARTE’S GULL IN THE SIERRA SAN PEDRO MÁRTIR, BAJA CALIFORNIA

     On 11 December 2015, during a snowstorm, De León-Girón found a Bonaparte’s Gull (Chroicocephalus philadelphia) unable to fl and at the point of starvation near the ranger offi of the Sierra de San Pedro Mártir National Park. Th location is 30° 59′ N, 115° 33′ 21″ W, at an elevation of 2518 m, and the vegetation is coniferous forest dominated by Pinus jeffeyi (Delgadillo-Rodríguez 2004). Th bird died two days later. Th specimen, an adult male, was prepared and deposited at the Universidad Autónoma de Baja California (UABC 2072; Figure 1). Th pectoral mass of the dissected specimen confimed the starved condition of this individual when it was found in the park during the snowstorm. Measurements include total length 360 mm, wingspan 725 mm, tarsus 35 mm, wing length 237 mm, tail 106 mm, exposed culmen 29 mm, and mass 115 g, barely half the mean of 222 g reported for males by Burger and Gochfeld (2002).

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    Clayton Anderson (Author)

    BOOK REVIEW: The Home Place: Memoirs of a Colored Man’s Love Affair with Nature

     As I read Th Home Place I felt honored to hear the story of another black birder. Statements like “Nature was oftn the fist and last thing on my mind, morning to night” and “I felt closer to flght by bringing the birds closer to my earthbound existence” could have been peeled directly out of my mind. But on another level, the statement “Responses in forest and fild are not born of any preconceived notions of what ‘should be.’ Thy lie only in the fact that I am.” went straight to my heart.

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    David Koeppel (Author)

    BOOK REVIEW: American Birds: A Literary Companion

     Th joy of watching birds in their natural environs has never found sole expression in moments of quiet, self-contained exhilaration. For all its characterization as a mash-up of solitary intellectual activity and a sport of personal bests, birding as a pastime has never been exclusionary or arcane. Who among us—serious birder or casual observer—hasn’t turned a memorable moment in the fild into a relatable tale of discovery and exuberance? Some have gone even further, communicating their ecstasy with the aid of the paintbrush, the camera, or the pen.

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    FLOYD E. HAYES, VIVEK KHANZODE (Author)

    SANDERLING SCAVENGING CRAB FRAGMENTS FROM A FORAGING WESTERN GULL

     Th Sanderling (Calidris alba) normally forages on a variety of live prey (Macwhirter et al. 2002). Thre are only a few previous reports of Sanderlings scavenging dead prey, including the carcasses of dead jellyfih and fihes on beaches (Gochfeld and Burger 1980, King 1981, Grimm 1984, Reneerkens et al. 2009). In two of these reports the Sanderlings scavenged fih carcasses aftr they had been ripped open by scavenging Herring Gulls (Larus argentatus; Gochfeld and Burger 1980) or Lesser Black-backed Gulls (L. fuscus; King 1981). In this note we document a Sanderling scavenging a crab preyed upon by a foraging Western Gull (L. occidentalis).