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American Avocet
Recurvirostra americana
Order
CHARADRIIFORMES
– Family
RECURVIROSTRIDAE
Authors: Robinson, Julie A., Lewis W. Oring, Joseph P. Skorupa, and Ruth Boettcher
Revisors: Ackerman, Joshua T., C. Alex Hartman, Mark P. Herzog, and John Y. Takekawa

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Introduction

Breeding adult male American Avocet.
Fig. 1. Distribution of the American Avocet.

It “enlivens the bleakest yet most characteristic of Great Basin summer landscapes – the shallow, foul bodies of alkaline or brackish water and their fringing flats of mud, alkali, or salt….” (Ryser 1985: 180).

This large, striking shorebird with long bluish-gray legs, a long recurved bill, and a black-and-white chevron pattern on its back and wings is one of four Avocet species in the world, the only one with distinct breeding and non-breeding plumages -- its grayish-white head and neck feathers become cinnamon in early spring as birds begin to form pairs and migrate to breeding areas.

The generic name Recurvirostra comes from the Avocet’s long recurved, or up-turned bill, used for both visual and tactile feeding on invertebrates. The name Avocet comes from the Italian avosetta, which means ‘graceful bird’. Its melodic alarm calls are a characteristic feature of the shallow alkaline wetlands of western and mid-western North America where it breeds in semicolonial groups.

During the breeding season, pairs engage in an elaborate sequence of pre-copulatory and post-copulatory displays culminating in an elegant Bill-crossed Run display following copulation. Both the male and female build the nest, incubate eggs, and care for precocial young. Avocet parents are noted for their deceptive and aggressive anti-predator behaviors, used when a potential predator is near their nest or young.

American Avocets specialize in using ephemeral wetlands of the arid western United States, and are iconic symbols and effective indicators of environmental stressors within western wetlands. Wide-ranging among seasons, Avocet migratory movements illustrate the importance of wetland connectivity at a large, landscape scale. American Avocets breed in large numbers within wetlands of the Great Salt Lake, Utah; San Francisco Bay, CA; and the Tulare Basin of California; pairs nest at lower abundances across the northern Great Basin, California’s Central Valley, the Prairie Pothole Region, and the western Great Plains. During winter, avocets occur in loose flocks at coastal and interior wetlands of the southern and southwestern United States and adjacent Mexico.

This species was extirpated from much of its eastern range by the beginning of the 20th century. The current population status of American Avocets is not well known, but it is estimated at 450,000 individuals (Brown et al. 2001, Morrison et al. 2006). Presently, populations are likely stable but reduced relative to pre-settlement times owing to drastic loss of wetlands.

Key threats to American Avocets are loss of wetland habitat, especially ephemeral wetlands, and contamination. In the arid west, wetlands compete with urban and agricultural areas for limited supplies of fresh water. Many wetlands that were once important Avocet breeding areas have declined in size by as much as 90%. Selenium and methylmercury contamination of wetland breeding areas also is a conservation issue. Wetland conservation and restoration efforts in inland areas of western North America will be important for maintaining populations of this bird. Restoring wetlands for optimal breeding habitat for American Avocets appears possible, with several examples of wetland mitigation for contamination and habitat loss in California’s Tulare Basin and San Francisco Bay.