Bird of the Month: American Avocet
Written by Andy McCormick
Andy McCormick, Volunteer and Former Board President of Eastside Audubon
An elegant wader, the American Avocet in Washington is a bird of small ponds of the Columbia Basin.
The lovely American Avocet is an immediately identifiable shorebird. In breeding plumage, the burnt orange colored head and neck is striking against the black and while body and blue legs. The dramatic upwardly recurved bill adds to this bird’s distinctive appearance. The avocet uses this bill for feeding by waving it like a scythe through the water using the bill’s sensitive sense of touch to locate larvae and small crustations. At times an entire flock can adopt this back-and-forth motion in unison.
The American Avocet is one of four worldwide members of the genus Recurvirostra. The other three are Pied Avocet (R. avocetta) of Eurasia, Red-necked Avocet (R. novaehollandiae) of Australia, and Andean Avocet (R. andina) of the high Andes. All have a recurved bill which gives the genus its name from the Latin recuruo, to bend back, and rostrum, the snout or muzzle of an animal or bill of a bird (Holloway).
MIGRATION AND DISTRIBUTION
American Avocet
Scientific Name: Recurvirostra americana
Length: 18”
Wingspan: 29”
Weight: 6 oz (160 g)
AOU Alpha Code: AMAV
American Avocets which migrate through the Pacific Northwest are most likely those that wintered along the California Coast or in the lower Colorado River Valley in California and Arizona (Paulson; Ackerman). Beginning in March, these avocets spread over a wide area in the Western United States and southern portion of the western Canadian provinces. Fall migration is more protracted beginning in July and lagging into October. Large numbers of avocets follow a lateral migration route to the west before heading south.
This avocet breeds near shallow alkaline ponds in the interior west from southeastern British Columbia and southern Saskatchewan and Manitoba through the interior western United States east of the Cascade and Sierra Nevada ranges, south to Arizona, New Mexico, and Texas, and also in the Central Valley of California. In Washington, avocets breed in the Columbia Basin region. However, during fall migration avocets can be found west of the Cascades toward the Pacific coast.
BREEDING AND YOUNG
Photo by Bob Bowhay
Once on the breeding territory, American Avocets decrease flocking and form pair bonds. Their showy copulation display ritual begins with both birds in shallow water. The female adopts a Solicitation Posture with her neck extended and bill in or near the water. The male in turn displays Sexual Preening by bringing water to its chest on the side facing the female which maintains a stance parallel to the male. Following more active preening and vigorous splashing of water, the male balances on the back of the female and cloacal contact is made. While alighting the male extends a wing over the female and with necks entwined and bills crossed, the pair makes a Bill-crossed Run for 3-7 meters (Ackerman et al). See the Macaulay Library for videos of this behavior and other photos and vocalizations.
Photo by Mick Thompson
American Avocets often prefer the protection of islands for nesting even when the water is shallow. The avocet nest can be a simple scrape in the soil, or a scrape lined with pebbles or local vegetation (Ackerman et al). As with other shorebirds, four eggs are deposited and incubated by both adults. Downy young leave the nest soon after hatching and begin foraging for their own food. First flight occurs in about four weeks (Kaufman).
HABITAT AND CONSERVATION
The preferred habitat for American Avocets is a shallow pond such as ephemeral spring ponds that dry out in summer. These temporary ponds create many suitable locations for breeding. However, many of these temporary wetlands are located on agricultural lands. In fact, some survey research data indicate that up to 80% of Black-necked Stilts and American Avocets summering in California’s Central Valley were found in environments created for agriculture, water management, and industry (Ackerman et al).
This annual increase in potential nesting locations also brings the threat of selenium and methylmercury contamination from chemicals used in agriculture. Accumulation of these substances in avocets and stilts has been shown to impair chick survival and growth. Conservation efforts aim to provide clean nesting and foraging habitat. In California, both the Tulare Lake basin and San Francisco Bay area wetlands have been reconstructed in the areas formerly used for salt evaporation ponds. Shallow water and construction of islands in the wetlands have enhanced breeding opportunities for avocets.
Photo credit Bob Bowhay and Mick Thompson.
References available upon request from amccormick@eastsideaudubon.org
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