Distribution: The distribution of the black-necked stilt, Himantopus mexicanus, like that of the American avocet, is highly dependent on suitable local habitat, making the breeding range somewhat spotty and localized. The black-necked stilt breeds in North America in the western and west-central United States, the Gulf and Atlantic Coasts, Baja California, western Mexico, southwest-central Canada, and portions of the Bahamas and West Indies. It also breeds in Central America, much of Mexico, and South America.
The stilt winters from northern California, Sonora, the Gulf Coast, and central Florida south locally through Central America, the West Indies, and South America to the limits of the breeding range (American Ornithologists' Union 1998, Terres 1991)). Resident populations occur in coastal southern California, western Mexico, the Gulf Coast, and southern Florida (Peterson 1990, National Geographic Society 1987).
Ecology: The primary foods for the black-necked stilt are invertebrates of the water column and flying insects near the water's surface. Small fish, crayfish, and seeds are also consumed. Stilts forage on bare ground and while wading in water in depths up to 15 cm, usually in water fresher than avocets prefer. Black-necked stilts can be found foraging along the shallow borders of freshwater and alkaline lakes, brackish ponds, salt marshes, and wet pastures (Terres 1991).
Birds arrive in Utah in early April (Roy 1998). Very little information exists as to where and when pair formation occurs among stilts. Observations made by Sordahl in the 1970's suggest that black-necked stilts do not form pair bonds until reaching the breeding grounds (Sordahl 1984). Stilts build their nests in loose colonies, sometimes with avocets. Nest sites are similar to those of avocets - located in areas with very sparse vegetation that afford an unobstructed view in all directions. Locations are generally on islands, dikes, or other areas associated with the water's edge. Nests are built on the ground, scraped into bare mud usually near patches of saltgrass or salicornia (Distichlis, Salicornia), and then lined with small bits of weeds, grasses, twigs, shells, or bones (Sordahl 1996, Terres 1991). The black-necked stilt is a monogamous species. It is believed that both sexes share in the site selection and building of the nest, but there is little written documentation of this belief. An average clutch size for the black-necked stilt is 4 eggs. The eggs are pyriform to long pyriform shaped, approximately 3cm x 4.5cm, buff colored and irregularly marked with dark brown or black spots. Incubation is shared by both sexes, alternating throughout the day and night, and lasts 22-26 days (measured from the day the first egg is laid to the day first egg is hatched. Chicks are precocial, downy, and able to feed themselves (Erlich et al. 1988). After a day or two the parents move the brood to areas more suitable for feeding and hiding from predators. The brood is cared for by both parents, but as the chicks mature the parents will begin to leave the brood. At about day 28 the young are able to fly, and are usually on their own, the parents having departed 1-2 weeks earlier (Sordahl 1996, Terres 1991). Similar to avocets, stilt juveniles will spend time in flocks with other stilts and depart for wintering grounds in small flocks beginning in August and throughout September. Birds have been observed at Bear River Refuge as late as mid-November (Roy 1998).
Habitat Requirements: Nesting occurs in areas with salt ponds, potholes, or shallow alkaline wetlands. It also occurs in mudflats of inland lakes, impoundments, and evaporation ponds. The birds feed in open water generally fresher than that chosen by avocets, from 0-15 cm deep, or on dry ground. The nests are usually built on islands or dikes with sparse vegetation. In desert wetlands, particularly in Utah, stilts nest along lake shorelines among scattered patches of vegetation, along barren mudflats, or on small patches of vegetation over water. Wintering habitats include intertidal mudflats and brackish-water impoundments (Robinson et al. 1997).