Western Birds Journal

Volume 32, No. 3

Published July 1, 2001

Issue description

Volume 32, number 3 of Western Birds, published 2001

Articles

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    JOHN P. KELLY (Author)

    DISTRIBUTION AND ABUNDANCE OF WINTER SHOREBIRDS ON TOMALES BAY, CALIFORNIA: IMPLICATIONS FOR CONSERVATION

    I analyzed the distribution and abundance of wintering shorebirds (Scolopacidae, Charadriidae, and Recurvirostridae) in Tomales Bay, California, on the basis of 57 baywide counts conducted over 10 years, from 1989–90 to 1998–99. Tomales Bay supports up to 20,689 shorebirds in early winter, thus qualifying as a wetland of "regional" importance in the Western Hemisphere Shorebird Reserve Network. Minimum overall shorebird abundance fell as low as 1,291 in late winter. Tomales Bay supported approximately a third of the wintering shorebirds in the Point Reyes/Bodega area in early winter.

    Observations of tidally structured flock movements of several species suggested that the northern and southern ends of Tomales Bay are occupied by different wintering groups. In association with cumulative seasonal rainfall, most species declined in abundance significantly in midwinter. The Sanderling and Marbled Godwit increased with cumulative rainfall in the north and south bay, respectively, suggesting weather-related influxes from outer coastal beaches.

    After accounting for the effects of cumulative seasonal rainfall and a 10-year trend in annual rainfall, I detected no long-term trends in species' abundances. Foraging and roosting shorebirds at the northern end of the bay were vulnerable to direct disturbance from concentrated recreational use. Long water-residence times in southern Tomales Bay suggest that shorebirds there may be particularly vulnerable to toxic spills or anthropogenic eutrophication. The closeness of San Francisco Bay implies a high potential for invasion of nonnative organisms established there, which could alter the availability of benthic prey to shorebirds in Tomales Bay.

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    MARK K. SOGGE, JENNIFER C. OWEN, EBEN H. PAXTON, SUZANNE M. LANGRIDGE, THOMAS J. KORONKIEWIC (Author)

    A TARGETED MIST NET CAPTURE TECHNIQUE FOR THE WILLOW FLYCATCHER

    We developed a targeted mist-netting technique designed to capture Willow Flycatchers (Empidonax traillii) at their breeding sites. The technique uses a variety of conspecific vocalizations to lure territorial flycatchers into mist nets. Songs and calls are broadcast from a portable CD player with speakers placed on both sides of the net. By playing vocalizations commonly heard during territorial interactions and switching the sound output from one speaker to the other, flycatchers are readily drawn into the nets.

    This capture technique is highly effective, captures birds of both sexes, and worked at sites throughout the Willow Flycatcher's breeding range and on its Central American wintering grounds.

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    THOMAS GARDAL, ALVARO JARAMILLO (Author)

    FURTHER EVIDENCE FOR A POPULATION DECLINE IN THE WESTERN WARBLING VIREO

    Recently, Gardali et al. (2000) reported that mist-net capture rates of breeding and migrating Western Warbling Vireos (Vireo gilvus swainsonii) had declined in Marin County, California, from 1979 to 1997. However, evidence of a population decline from a single site may be misleading and could simply represent site-specific changes in abundance.

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    TERENCE R. WAHL (Author)

    BRANDT'S CORMORANT SINKS AT SEA

    Cormorants' limited degree of plumage waterproofing, the spread-winged posture attributed to the need to dry their feathers, their need to rest and roost out of the water, and their nearshore foraging distribution have been commented upon by many (e.g., Schneider and Hunt 1984; Boekelheide et al. 1990; Siegel-Causey and Litvinenko 1993). I am unaware of descriptions of consequences for cormorants should they be unable to leave the water before reaching saturation.

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    ANDREW W. PISTON, STEVEN C. HEINL (Author)

    FIRST RECORD OF THE EUROPEAN GOLDEN-PLOVER (PLUVIALIS APRICARIA) FROM THE PACIFIC

    The European Golden-Plover (Pluvialis apricaria) breeds from Iceland and the British Isles east to the base of the Taimyr Peninsula, Russia, at about 102°30′E (Vaurie 1965). Virtually the entire population migrates to or through Europe to winter in the British Isles, western Europe, and throughout the Mediterranean Basin. Small numbers winter as far east as the southern Caspian Sea and occasionally to eastern India, and small numbers winter on the Atlantic coast of Africa, occasionally south to Gambia (Vaurie 1965; Cramp 1983).

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    Steve N. G. Howell (Author)

    BOOK REVIEWS : United States Shorebird Conservation Plan

    Shorebirds may not be as commercially valuable as waterfowl, or as widely appreciated by the general public as songbirds, yet they have long held a special fascination for birders and ornithologists. The spectacular migrations undertaken by some species, and the wild regions they often inhabit, stir both the soul and the mind. Until recently, however, most shorebirds have tended to slip through the cracks in conservation consciousness. Yet their highly migratory habits, their need to concentrate at a few food-rich sites, and their use of habitats prone to human disturbance and development combine to make shorebirds vulnerable at many levels.

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    Gregory H. Golet (Author)

    BOOK REVIEW :The Riparian Bird Conservation Plan

    Habitat loss may be the leading cause of population declines and range reductions among landbirds in western North America. To reverse this trend and maintain existing populations, remnant high-quality habitats must be protected and degraded habitats restored.

    Although efforts to protect and enhance riparian habitats are underway, land managers designing restoration programs face a high degree of uncertainty in deciding which management actions will be most effective. To reduce this uncertainty, the full range of knowledge and skills from the natural and social sciences should be brought to bear on the problem. In addition, dissemination of information among scientists, managers, and stakeholders should be rapid, reciprocal, and continuous (Mangel et al. 1996).

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    JON L. DUNN, KIMBALL L.GARRETT (Author)

    FEATURED PHOTO : PARAPATRY IN WOODHOUSE'S AND CALIFORNIA SCRUB-JAYS REVISITED

    Geographic variation in the scrub-jays (the Aphelocoma coerulescens species group) has intrigued and confounded ornithologists both before and since Pitelka's (1951) extensive review. In part on the basis of the work of Peterson (1990, 1992), the American Ornithologists' Union (1995) elevated the widespread continental scrub-jays (A. californica, the "Western Scrub-Jay") and the endemic jay of Santa Cruz Island (A. insularis, the "Island Scrub-Jay") to full species rank, restricting the name Aphelocoma coerulescens to the isolated Florida Scrub-Jay.

    Components of the Western Scrub-Jay have at times been given full species rank, in the form of a division between birds of the Pacific coast (the A. [c.] californica group of subspecies, hereafter "California Scrub-Jay") and birds of interior western North America (the A. [c.] woodhouseii group, "Woodhouse's Scrub-Jay"); an additional group of subspecies (the "Sumichrast's Scrub-Jay," A. [c.] sumichrasti) occurs on the southern Mexican plateau. Woodhouse's and California Scrub-Jays were treated as separate species most recently by Swarth (1918).