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7329 Silverado Trail
Napa, CA 94558
2109 Arch Airport Rd
Stockton, CA 95206
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Stanislaus River Basin and Calaveras River Water Use Program
Threatened and Endangered Species Report - March 1995
Bay Delta and Special Water Projects Division, CA Dept. of Fish and Game
Long-billed CurlewNumenius americanus
California Department of Fish and Game "Species of Special Concern"
Life HistoryThis is a large, 23 inches in length, buffy-brown shorebird. It has a very long, sickle-shaped bill which measures four to eight and one-half inches; the juveniles have shorter bills. This bird somewhat resembles the whimbrel but is larger, much more buffy in color, and lacks the bold crown stripes.
This shorebird is an uncommon to fairly common breeder from April to September in the wet meadows of northeastern California in Siskiyou, Modoc, and Lassen counties. They are uncommon to locally very common as a winter visitor from early July to April along most of the California coast and also in the Central and Imperial Valleys. The preferred winter habitats of the curlew are large coastal estuaries, upland herbaceous areas, and croplands. Small numbers of nonbreeders remain on the coast in the summer, and larger numbers remain during some years in the Central Valley (Cogswell 1977, Page et al 1979, Garrett and Dunn 1981). Outside California, this curlew is found in southern Canada and the western United States. They winter from California and Louisiana to Guatemala, and from South Carolina to Florida.
Curlews are generally solitary nesters but may choose to be loosely colonial within favorable habitats such as gravelly soils on gently rolling terrain (Steinart 1975). The nest of the curlew is usually located in a relatively flat area with a grass cover of four to eight inches high and is a sparsely-lined depression remote from water (Palmer 1967). The nest will often be placed close to cover such as a clump of grass, a rock, or mound of soil. In California, nests are on elevated interior grasslands and wet meadows, usually adjacent to lakes or marshes (Grinnel and Miller 1944). The mean clutch size is four eggs which are incubated for a period of 27 to 28 days by both members of the pair. The precocial young (covered with down and fully active) are cared for by both parents. The fledgling period is 41 to 45 days (Johnsgard 1981).
These shorebirds exhibit a yearlong, diurnal activity. They probably feed at night in estuarine habitats. In the winter they make periodic short flights from the intertidal mudflats to their high tide roosts. The fall migrants begin arriving on the central coast of California in late June. By approximately mid-April most of the curlews have left for their breeding grounds. Slightly higher numbers of migrants occur in fall than in the spring migration (Page et al. 1979).
The long-billed curlew uses its distinct long bill to probe deep into the substrate or to grab prey from mud surfaces. Prey consists of mud crabs, ghost shrimp, and mud shrimp. They have also been reported to forage on insect pupae, gem clams and small estuarine fish. Inland, the curlew takes insects (adults and larvae), worms, spiders, berries, crayfish, snails, grasshoppers, and small crustaceans (Bent 1929).
Findings and ConclusionsThe long-billed curlew is a "California species of special concern" because of declining numbers probably caused by agricultural practices (Tate 1981). The breeding range has receded considerably in the last 80 years.
Long-billed curlews were not observed or reported with the study reaches as defined. They probably do, however, use the open grasslands areas adjacent to the river. Only those projects that would affect the grasslands could have negative impacts to this species.