Western Birds Journal

Volume 45, No. 1

Published January 1, 2014

Issue description

Volume 45, number 1 of Western Birds, published 2014

Articles

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    MARTIN MEYERS (Author)

    2012 NEVADA BIRD RECORDS COMMITTEE REPORT

     This report covers the 99 records reviewed by the Nevada Bird Records Committee in 2012, of which 87 were endorsed. These 99 records cover sightings from 1 June 1954 through 27 August 2012. One species is added to the Nevada list (and to the committee’s review list): the Red-bellied Woodpecker (Melanerpes carolinus). Two species are removed from the review list because of the high number of records or regularity of occurrence. The Nevada state list now stands at 489 species, of which 164 are currently on the review list.

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    MICHAEL C. McGRANN, JAMES H. THORNE (Author)

    ELEVATIONAL RANGES OF BIRDS ALONG CALIFORNIA’S PACIFIC CREST TRAIL

    Climate change is predicted to affect the ranges of montane birds differently, depending on their ecological adaptations to regional conditions. Detailed regional data on species’ distributions from a systematic survey are crucial for tracking these range shifts and for guiding conservation decisions. We systematically completed 3578 point counts along a 2736-km mega-transect by following the Pacific Crest Trail (PCT) from 2 April to 8 September 2006. On this basis, we describe the elevation ranges of 74 common bird species and their habitats along the PCT by five segments: southern California, southern and northern Sierra Nevada, southern Cascade Range, and Klamath Mountains. We also identify potential sampling bias caused from seasonal variation in the detectability of birds by region. This assessment of bird distributions over a wide range can permit future efforts to gauge the responses of large numbers of common birds to land use and climate change.

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    DANIEL S. COOPER, LINNEA S. HALL, ADAM J. SEARCY (Author)

    A POPULATION CENSUS OF THE CACTUS WREN IN VENTURA COUNTY, CALIFORNIA

    The Cactus Wren (Campylorhynchus brunneicapillus) is a polytypic species widespread in the southwestern U.S. and northern Mexico. Though closer in plumage characteristics to the desert subspecies anthonyl, populations resident in coastal sage scrub on the coastal slope of Ventura County and Los Angeles County occupy an ecological niche more similar to that of the more southerly subspecies sandiegensis. Because of fragmentation of habitat associated with urbanization, the populations on southern California’s coastal slope are almost entirely isolated from those of the deserts, and apparently from each other. They are declining precipitously for reasons not entirely understood but certainly related to loss, fragmentation, and degradation of suitable habitat. In 2012, we organized a volunteer effort to map the entire population in Ventura County and found 111 active, accessible territories with at least one adult or a fresh nest. Additional areas to which we did not have access could raise this total number to 166 territories county-wide. While historically the species occurred somewhat more widely in the eastern portion of the county, all active territories now appear to be restricted to a narrow band of cactus-rich scrub at the far western edge of the Santa Monica Mountains and Simi Hills, from Point Mugu northeast through Thousand Oaks to the west side of Simi Valley, roughly tracking the distribution of large patches of prickly-pear (Opuntia spp.) and coast cholla (Cylindropuntia prolifera).

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    TED FLOYD (Author)

    DOCUMENTATION BY SOUND SPECTROGRAM OF A CRYPTIC TAXON, VIREO G. GILVUS, IN BOULDER COUNTY, COLORADO

    During June and July 2011, I audio-recorded eight Warbling Vireos (Vireo gilvus) at widely scattered sites in eastern Boulder County, Colorado, immediately east of the steep foothills of the Rocky Mountains. All eight sang songs like those of the eastern subspecies, V. g. gilvus; immediately to the west, in the steep foothills of the Rocky Mountains, Warbling Vireos sing songs like those of the western subspecies, V. g. swainsonii. The results of these observations suggest both the presence of nominate gilvus farther west in Colorado than previously documented and a sharp demarcation between the breeding ranges of swainsonii and gilvus.

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    COLE J. CALDWELL (Author)

    FORAGING INTERACTIONS OF THE GREAT EGRET IN UPLAND HABITATS

    Great Egrets (Ardea alba) foraging in grassy uplands near Arcata, California, used multiple strategies, foraging solitarily or in groups and commensally or noncommensally, in any of the four possible combinations. Egrets foraging commensally with cattle apparently benefited from the association on eight of the 21 observed occasions. Solitary foragers tended to use microhabitats along ditches and fences and were generally less active, made fewer errors, and captured larger prey than did group and commensal foragers. But group foragers, commensal and noncommensal foragers combined, captured more prey. Tidal fluctuations, prey types, and habitat structures likely modified foraging behaviors. There was no clear difference in rate of food intake, handling time, or foraging success by foraging strategy: a higher rate of capture of small prey by egrets foraging in groups compensated for the lower rate of capture of larger prey by solitary birds.

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    JAMES R. TIETZ (Author)

    BOOK REVIEW: Birds of the Sierra Nevada: Their Natural History, Status, and Distribution

    The Sierra Nevada’s varied habitats of forest, chaparral, and alpine meadows, combined with its splendid mountainous scenery, have made this range a favored destination for tourists and bird watchers. For over a century, professional ornithologists and amateur field naturalists have studied the rich avifauna of this region, but until now a comprehensive guide to the full expanse of the Sierra Nevada did not exist. In 1977, David Gaines wrote the Birds of the Yosemite Sierra: A Distributional Survey, which covered both the western and eastern slopes of the Sierra Nevada but was limited to the area around Yosemite—it was updated in 1988 as Birds of Yosemite and the East Slope. Published in 1985, Discovering Sierra Birds, by Edward Beedy and Stephen Granholm, covered the western slope only and focused on Yosemite, Kings Canyon, and Sequoia national parks. The need for a book covering the entire Sierra Nevada, with additional information on natural history, population status, and conservation, was expressed by the late Steve Medley, former president of the Yosemite Association, in 1998. And now, after 15 years of devoted labor, the Birds of the Sierra Nevada: Their Natural History, Status, and Distribution has been completed. It includes many passages from Discovering Sierra Birds, but with so much additional information and entirely new illustrations, it is much more than just an update.

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    KEN R. SCHNEIDER (Author)

    FEATURED PHOTO: HYPERMELANISM IN AN AMERICAN PIPIT

    On 1 December 2013, I observed an unusual pipit in a flock of American Pipits (Anthus rubescens) at Bedwell Bayfront Park in Menlo Park, San Mateo County, California. The bird appeared structurally similar to the other pipits in the flock, but its plumage was much darker overall (see this issue’s back cover). The whitish to buff areas on the face, underparts, and tips of the median and greater wing coverts of a normally pigmented pipit were replaced by dark brown. The legs and bill were also darker than the corresponding bare parts of the nearby pipits. The bird did show what appeared to be normal pale edges on the tertials, but brief glimpses of the rectrices failed to reveal the expected white in the outer tail feathers. I observed this individual again at the same location on 8 December 2013 and obtained several photographs. Although I initially considered the possibility of a vagrant pipit species, the structural characteristics and other field marks identify the bird as an aberrantly colored American Pipit, the only species of pipit expected in the area. In particular, the essentially concolorous upperparts and underparts of this bird rule out even dark pipit species such as the Rock Pipit (Anthus petrosus), which still have a contrastingly lighter breast and belly.