American avocet

The American avocet call has been described as both a shrill and melodic alarm bweet, which rises in inflection over time.[6][7][8]

American avocets breed in anything from freshwater to hypersaline wetlands in the western and mid-west United States.[7][9] American avocets form breeding colonies numbering in dozens of pairs.[10] Throughout the breeding season, birds pair off in a series of copulatory displays.[7] After breeding, the birds gather in large flocks, sometimes amounting to hundreds of birds. Nesting takes place near water, usually on small islands or mucky shorelines where access by predators is difficult. Together, the male and female build a saucer-shaped nest, take turns incubating the four eggs, and tending to the precocial young.[7] Upon hatching, the chicks feed themselves; they are never fed by their parents.[10]

Avocets tend to prefer habitats with fine sediments for foraging.[11] In the winter, these birds feed extensively on brine shrimp. Usually, this entails the avocet pecking while walking or wading on the shore, but it can also swim to expand foraging area. During the breeding season, avocets continue to eat brine shrimp but switch mainly to consuming brine flies. Brine flies and brine fly larvae are so abundant in avocet breeding grounds that they often blacken the surface of any exposed mud. Brine flies sustain the avocet during its breeding season.[2] The avocet employs both visual and tactile methods of feeding.[7] The primary visual feeding method is pecking at flies. However the avocet will also feed by plunging (wherein the head and neck of the bird are submerged), snatching (wherein the bird catches a flying insect), and bill pursuit (wherein the bird repeatedly opens and closes its bill while moving its head along the surface of the water). Methods of tactile feeding include filtering, scraping, and scythe feeding.[2]

Shooting and trapping of American avocets led to population decline until the 1900s. During this time, the species was extirpated from most of the East Coast of the United States.[7] By 1918, Avocets became protected under the Migratory Bird Treaty Act (16 U.S.C. 703-712). Since that time, other threats have emerged. Contaminants and toxins such as DDT, selenium, and methylmercury, have had significant impacts on American avocet breeding success, especially because Avocet chicks are more susceptible to environmental disruptions than adults.[7][9] The avocet also faces habitat loss. While agricultural and industrial environments have become alternate habitat for the avocet, natural wetlands are decreasing rapidly.[7]

John James Audubon's depiction of the American avocet in breeding plumage.

In his famous The Birds of America, John James Audubon describes a day of stalking and spying on the avocet. He judiciously noted their foraging, nesting, defensive, and flight behaviors.[6] See his painting to the right.