American Avocet

Breeding season runs from April through June, with most pairing taking place before or during spring migration and birds arriving on breeding grounds in early April. Some individuals show natal philopatry — returning to breed near where they hatched. Pairs are monogamous within a single season.

Courtship displays are elaborate and can be initiated by either sex. They involve crouching and bowing postures both in and out of water, dancing with outspread wings, and swaying from side to side. The male preens himself with water, gradually escalating to frenzied splashing just before mating. After copulation, the pair crosses bills and intertwines their long necks, then runs forward together — sometimes with the male draping a wing over the female. A group display called "circling" involves two pairs (or a pair and a third individual) facing each other, stretching their bills toward one another while calling and rotating in a circle. Nesting is colonial, in loose groups sometimes mixed with Black-necked Stilts.

Both sexes select the nest site together — the male leads the female around making scrapes until they agree on a spot. The nest is a shallow scrape in bare ground, sometimes lined with grass, feathers, pebbles, or shells; some nests are completely unlined. If rising water threatens to flood the nest, additional lining is added and the structure can be built up into a mound more than 30 cm tall. Clutch size is 3–5 eggs, with 4 most common. Eggs are olive-buff to greenish-brown, blotched with dark brown and black spots, and pointed at one end — a shape that prevents them rolling away on bare ground. Eggs are laid at intervals of 1–2 days.

Incubation lasts 23–25 days, with both parents taking turns during the day; the female incubates alone at night. Chicks are precocial — downy, open-eyed, and able to walk, swim, and even dive underwater within 24 hours of hatching. Both parents tend the young, though chicks find all their own food from the start. First flight occurs at 4–5 weeks. One brood per year.

The species also practices brood parasitism in both directions. Females sometimes lay eggs in the nests of other avocets or even Mew Gulls. But avocet nests are also parasitised by Common Terns and Black-necked Stilts — and in at least one documented case, avocets successfully reared Black-necked Stilt hatchlings as their own chicks.

The typical lifespan of an American Avocet in the wild is 9–15 years, with the maximum recorded age for a wild bird standing at 15 years based on banding data. In captivity, the species can live considerably longer — individuals in zoos have been recorded living more than 20 years, reflecting the absence of predation, disease pressure, and the physical demands of migration.

Survival rates in the wild are shaped by several factors. Precocial chicks are mobile from their first day but remain vulnerable to predation by foxes, corvids, gulls, and raptors during the first weeks of life. Adults face predation from birds of prey and mammalian predators at nest sites. Selenium contamination and methylmercury pollution in some western wetlands have been documented causing chick deaths and reproductive failure, reducing effective recruitment into the population. The physical demands of long-distance migration — including the need to stage at productive but increasingly threatened saline lakes — also impose mortality costs.

Compared to its closest relative in Europe, the Pied Avocet (Recurvirostra avosetta), the American Avocet has a broadly similar lifespan, though the Pied Avocet holds a remarkable longevity record of nearly 28 years in the wild based on European ringing data. Both species are long-lived relative to their body size, a pattern typical of shorebirds that invest heavily in parental care and have relatively low annual reproductive output.

The American Avocet is listed as Least Concern on the IUCN Red List, with a global population estimated at approximately 450,000–460,000 individuals by Partners in Flight and BirdLife International. The North American Breeding Bird Survey found populations broadly stable between 1966 and 2015, and numbers wintering along the Atlantic Coast have increased substantially in recent decades. The species rates 11 out of 20 on the Partners in Flight Continental Concern Score and is not on the Watch List.

The picture was not always so stable. Overhunting in the 19th and early 20th centuries, combined with large-scale wetland drainage, extirpated the species from much of its eastern range and caused significant population declines across the west. The American Avocet is now protected under the US Migratory Bird Treaty Act, and the creation of sewage ponds, agricultural evaporation ponds, rice fields, and salt ponds has provided additional breeding and foraging habitat that has helped support recovery.

Selenium contamination remains a serious ongoing threat. When irrigation water leaches selenium from agricultural soils into wetlands, concentrations can reach toxic levels. The most notorious case occurred at Kesterson Reservoir in California's San Joaquin Valley in the 1980s, where selenium poisoning caused widespread embryo deformities, congenital disorders, and reproductive failure in waterbirds including avocets. Similar contamination affects wetlands across the western US today.

Climate change poses an increasingly urgent threat to the saline lakes that are critical staging and foraging sites. Lake Abert in Oregon — which can host up to 40,000 avocets in a single day during migration — went completely dry in 2014 for the first time since the 1930s Dust Bowl, due to a combination of drought, climate change, and upstream water diversions. The Great Salt Lake in Utah, where up to 250,000 avocets stage during migration, has been shrinking steadily. Audubon scientists project that the breeding range in Montana will shift north into Alberta and Saskatchewan as the climate warms. The Saline Lakes Act, enacted by Congress, has dedicated USGS funding to monitor these critical western wetlands.

Few North American shorebirds have a courtship sequence as elaborate as the American Avocet's. Pairing typically begins before or during spring migration, and displays intensify once birds reach the breeding grounds in April. Either sex can initiate courtship, and the full sequence involves a progression of increasingly intense behaviours.

Early displays involve crouching and bowing postures both in and out of water, with birds swaying from side to side and spreading their wings. As intensity builds, the male begins preening himself with water — dipping and flicking — gradually escalating to frenzied splashing just before mating. After copulation, the pair performs a distinctive post-mating display: they cross bills and intertwine their long necks, then run forward together, sometimes with the male draping a wing over the female's back. This physical intertwining of necks is one of the most visually striking pair-bonding behaviours of any shorebird.

A group display called "circling" adds a social dimension to courtship. Two pairs — or a pair and a third individual — face each other, stretch their bills toward one another while calling, and rotate slowly in a circle. The function of this display is not fully understood but is thought to reinforce pair bonds and establish social relationships within the colony. Nesting is colonial, with pairs often nesting in loose groups alongside Black-necked Stilts, and the circling display may help mediate interactions between neighbouring pairs. Both sexes participate in nest-site selection, with the male leading the female around making trial scrapes until a site is agreed upon — a collaborative process that itself reinforces the pair bond before egg-laying begins.

American Avocets are among the most aggressive nest defenders of any North American shorebird. When a predator — whether a fox, crow, gull, or human — approaches the nest, the response is immediate and coordinated. Adults launch into repeated dive-bombing runs, sweeping low over the intruder while calling loudly. Neighbouring pairs and even non-breeding birds often join in, creating a sustained aerial assault that can drive off much larger animals.

The acoustic component of these dives is particularly sophisticated. As an avocet swoops toward a predator, it gradually raises the pitch of its calls, simulating the Doppler effect — the acoustic compression that makes an approaching sound source seem higher-pitched. The result is that the bird sounds as though it is moving faster than it actually is, amplifying the perceived threat. This graded vocal system, documented by Sordahl (1986), is one of the most precisely described examples of acoustic deception in any bird species.

When eggs or chicks face immediate danger, avocets also perform a broken-wing or distraction display, dragging themselves along the ground with one wing held out as if injured. This lures ground predators away from the nest before the adult suddenly "recovers" and flies off. The broken-wing call — a distressed screech quite unlike the normal wheep contact call — accompanies this display and adds to its convincing quality. Parent birds have also been observed building up nest mounds during flooding events, raising eggs above rising water rather than abandoning the clutch. Taken together, these behaviours represent a layered and flexible anti-predator toolkit that reflects the exposed nature of ground-nesting on bare, open flats.