The Lahontan Valley wetlands of Nevada are critical breeding, wintering, and migratory stopover sites for shorebirds and waterfowl and have been classified as a Hemispheric Reserve within the Western Hemisphere Shorebird Reserve Network (Myers et al. 1987, Harrington et al. 1989). From 1905 through 1987, wetlands in the Lahontan Valley declined from 34,800 to 6150 ha (Hoffman et al. 1990:5). In 1991, these wetlands were reduced further as Nevada experienced its fifth consecutive year of drought (Schaefer 1991). During 1991, I monitored breeding by American Avocets (Recurvirostra americana) and Black-necked Stilts (Himantopus mexicanus) in the extremely limited suitable habitat available to them in the Lahontan Valley. Here I report numbers of breeding recurvirostrids and discuss possible reasons for their success or failure in 1991.
Avocets and stilts feed in shallow wetlands and nest together in loose colonies (Hamilton 1975). Neighboring pairs work together in voicing alarm, mobbing potential predators, and performing distraction displays (Sordahl 1986, 1990). Like the well-studied Pied Avocet (R. avosetta) in Europe and Black Stilt (H. novaezelandiae) in New Zealand, they probably first breed at an age of 2 or 3 years and are relatively long-lived (Cadbury and Olney 1978, Christine Reed pers. comm.). Sordahl (1984) marked individual American Avocets and Black-necked Stilts and observed 20–30% return in the following breeding season; 60–90% of these birds had previously bred successfully.