American avocets are found in western North America from March through October and in coastal California, southern Texas, Florida, Louisiana and south to Guatemala in winter.

Biogeographic Regions: nearctic (Native ); neotropical (Native )

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Breeding

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) BREEDING: Northwest Territories (Kuyt and Johns 1992), southeastern British Columbia, central Alberta, southern Saskatchewan, southwestern Manitoba, southwestern Ontario, and Minnesota south locally to southern California, central Nevada, northern Utah, south-central Colorado, southern New Mexico, and San Luis Potosi, east to central Kansas and coastal Texas. Nonbreeders often in usual winter range in summer. NON-BREEDING: from California and southern Texas south through Mexico, casually to Guatemala, Belize, Honduras, and Costa Rica, locally in southern Florida.

Graceful and sleek, these long-legged waders have a black bill and light blue legs. Avocets are the tallest and longest-legged birds in their family. They are 400 to 500 mm in length and have a wingspan of 213 to 242 mm. They are often confused with black-necked stilts (Himantopus mexicanus), but are distinguishable by the bold black and white pattern on their back and wings and a strongly upcurved black bill. Females are similar in appearance to males but with a shorter and more upwardly-curved bill, male bills are longer and straighter. They are the only avocet with distinct breeding and non-breeding plumages. Breeding plumage is obtained in the first year and is a beautiful rusty cinnamon along the head and neck. Basic plumage is a gray head. Adult breeding plumage appears from January to March and is lost in July to September.

Average length: 400-500 mm.

Average wingspan: 213-242 mm.

Sexual Dimorphism: sexes shaped differently

Average mass: 340 g.

Length: 46 cm

Weight: 316 grams

No other North American shorebird with a recurved bill has both a white belly and bold black and white patterning on the folded wings and back.

• Terrestrial
• Freshwater
• Marine

American avocets are numerous in mudflats, ponds, wetlands, and freshwater marshes and swamps. They are also common in lakes, rocky/sandy seashores, bay/coastal islands, and tidal flats.

Habitat Regions: temperate ; tropical ; terrestrial

Aquatic Biomes: lakes and ponds; coastal ; brackish water

Wetlands: marsh ; swamp

Other Habitat Features: estuarine

Comments: Lowland marshes, mudflats, ponds, alkaline lakes, and estuaries (AOU 1983). At Humboldt Bay, California, wintering birds used intertidal mud flats (mainly for for feeding and resting), a sewage oxidation pond (mainly for feeding and secondarily as a source of fresh water), high elevation mud flats (early high tide roost), and islands in a brackish lake (primary high tide roost); typically roosted on shallow, submerged bars of islands in deep nontidal ponds or less often in shallow water or on exposed mud near the water's edge of tidal mud flats (Evans and Harris 1994). Availability of sewage oxidation pond at Humboldt Bay enhanced habitat; the wintering population increased from 30-35 in 1960 (before pond construction) to 500-800 in the 1980s (after pond construction) (Evans and Harris 1994). In coastal South Carolina, most nonbreeding birds used habitats with water 10-17 cm deep (and relatively stable level) and little or no exposed substrate; among several brackish ponds, salinity was not an important factor in habitat selection (Boettcher et al. 1995).

Usually nests on open flats or areas with scattered tufts of grass on islands or along lakes (especially alkaline) and marshes. Readily nests on artificial islands (such as those created for waterfowl) in impoundments (Giroux 1985).

In Northwest Territories, Kuyt and Johns (1992) found two instances of avocet eggs in gull nests.

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.

May be nonmigratory in certain southern portions of range. Northern interior breeding populations make extensive seasonal migrations. Migrates mainly through western U.S. At Humboldt Bay California, arrives late-August to mid-November, departs February to late April and early May (Evans and Harris 1994).

American avocets swoop their open bills back and forth in shallow water to catch aquatic insects. They may feed in flocks of up to 100 plus birds, in deep water they will "tip up" like dabbling ducks and are reportedly good swimmers.

Foods eaten include: Insects and other invertebrates, shrimp and other crustaceans, aquatic vegetation and seeds.

Animal Foods: insects; terrestrial non-insect arthropods; aquatic crustaceans

Plant Foods: leaves; seeds, grains, and nuts

Primary Diet: omnivore

Comments: Walks slowly through the water; often feeding in flocks that number 12-300 birds. Eats a variety of aquatic insects and their larvae, crustaceans, and seeds of aquatic plants, obtained mainly from soft muddy bottom or water surface. May extend head, or dive, under surface of water while feeding. During fall-winter-spring at Humboldt Bay, California, foraged on intertidal mud flats within 3 km of roosts, usually within 100 m of tide edge, most often when tide levels were between 0.5 and 1.2 m Mean Lower Low Water; in October, fed mainly at sewage oxidation ponds with concentrations of invertebrate prey (Evans and Harris 1994).

American avocets are important members of their ecosystem; because of their food habits they likely have a regulatory influence on insect and crustacean populations, and they are an important food source for their predators. They also have an influence on the plants and seeds they eat.

American avocets are mostly quiet and uncaring but become extremely aggressive on breeding and nesting grounds and protest loudly and dive bomb when intruders approach. They have few non-human predators, some known nest predators include skunks (subfamily Mephitinae) and foxes (family Canidae).

Known Predators:

• skunks (Mephitinae)
• foxes (Canidae)

100,000 - 1,000,000 individuals

Comments: Total population estimated at 450,000, with about 63,000 breeding in Canada (Morrison et al. 2001).

American avocets make loud "wheet" or "pleeet" and shrill "kleeap" sounds that are often repeated. They are very noisy when intruders approach active nests. They also communicate using complex displays that include dancing, bowing and crouching.

Communication Channels: visual ; acoustic

1 brood per year, usually 3-5 eggs laid which are a pale ashy-yellow or olive-brown covered evenly with dark brown spots and blotches. Eggs are laid at intervals of 1-2 days, with a full clutch in 5 days (Hayman et al., 1986; Soothill & Soothill, 1982; Nethersole-Thompson, 1986).

Banded American avocets have been recorded to live up to 9 years in the wild.

No records are available about life span in captivity, but presumably they live for 9 plus years!

Range lifespan

Status: wild: 9 (high) years.

Average lifespan

Status: wild: 168 months.

American avocets are monogamous and loosely colonial. Pairs perform elaborate courtship displays that involve various crouching and bowing postures in and out of water, dancing with outspread wings and swaying from side to side.

Mating System: monogamous

Breeding occurs between April and June. Nests are built on shore and are usually scrapes in the ground; they are sometimes lined with dry grass or mud chips. The female lays 3 to 5 eggs (4 on average); eggs are olive colored with brown and black spots. Incubation lasts 22 to 29 days and the eggs hatch synchronously. Fledging occurs after 28 to 35 days.

Breeding season: April to June

Range eggs per season: 3 to 5.

Range time to hatching: 22 to 29 days.

Range fledging age: 28 to 35 days.

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); fertilization

Average eggs per season: 4.

Both male and female American avocets incubate the eggs. Incubation lasts 22 to 29 days. The precocial young are cared for by both sexes but the young feed themselves. Fledging occurs after 28 to 35 days.

Parental Investment: no parental involvement; precocial ; pre-fertilization; pre-hatching/birth (Protecting: Male, Female); pre-weaning/fledging (Protecting: Male, Female)

Breeding begins in mid-April in the south, as late as mid-May in the north. Clutch size usually is 3-4. Incubation lasts 23-25 days, by both sexes. Young are precocial, tended by both adults, independent in about 6 weeks. Nests usually in a loose colony.

Currently protected by the US Migratory Bird Act, American avocets are making a comeback after over-hunting in the 19th and early 20th centuries. The main threats to American avocets today are habitat loss and degredation.

US Migratory Bird Act: protected

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

Canada

Rounded National Status Rank: N5B - Secure

United States

Rounded National Status Rank: N5B,N5N : N5B: Secure - Breeding, N5N: Secure - Nonbreeding

Rounded Global Status Rank: G5 - Secure

Reasons: Globally secure. Significant regional declines have not been reported.

Management Requirements: Readily nests on artificial islands (such as those created for waterfowl) in impoundments (Giroux 1985).

There are no known adverse affects of American avocets on humans.

American avocets are enjoyable to watch and are sought out by many birders.

Positive Impacts: ecotourism