Species Profile: Wilson's Phalarope

Nonconformist shorebird of prairie marshes

Photo: Bill Hubick

The Wilson’s Phalarope is a small, long-legged shorebird, with lobed toes and a dainty-looking, needle-like black bill. Sexual dimorphism is reversed in this species, the female being larger and more colorful than the male. The breeding female Wilson’s is a handsome bird, gray and brown above, with white flanks and underparts and a rich reddish neck, blending to orange at the breast. The breeding male is a duller version of the female, with a brown back, and the reddish neck reduced or absent. This role reversal confused early biologists, and led Audubon himself to mislabel male and female phalaropes in his illustrations.

In prairie marshes, it’s the female Wilson’s Phalarope who “rules the roost.” Phalaropes employ an uncommon mating system known as polyandry, where each female mates with more than one male. Female Wilson’s Phalaropes arrive on the breeding grounds first, stake out breeding territories, select nest sites, perform courtship rituals, and compete for mates.

Polyandry is a rare breeding strategy known from less than 1% of bird species, including several shorebird species, rheas, cassowaries, and others. Ornithologists speculate that this strategy evolved in species with low nesting densities, where remating opportunities are scarce for both sexes. Since male phalaropes would not benefit from deserting the nest, they remain to raise the young. The females remain free to lay another clutch if the opportunity arises. Newly hatched phalaropes are precocial, meaning they are mobile, can feed themselves, and do not need constant brooding.

Unlike its close relatives, the Red and Red-necked Phalaropes, the Wilson’s spends no time at sea, living instead on inland waters. It nests in sparse to dense vegetation in prairie potholes, wetlands, and upland fields. They feed on aquatic insects, flies, and small crustaceans. When staging or wintering on saline lakes, they also consume brine shrimp and brine flies. Wilson’s sometimes employ an interesting feeding strategy called “spinning”, where they swim rapidly in a tight circle to form a small whirlpool. This behavior is thought to assist in feeding by raising food from the bottom of shallow water.

When preparing to migrate, Wilson’s Phalaropes stage in great numbers on saline lakes, including Mono Lake in California and the Great Salt Lake of Utah (both ABC-designated Globally Important Bird Areas). They migrate to South America, wintering on shallow saline lakes in the Andes and south.

Although the species itself is still fairly common, ABC includes Wilson’s Phalarope on its WatchList due to threats to its nesting and staging habitats. Suitable wetlands are being lost to drainage, filling, industrial development, and conversion to agricultural crops. Habitat is also lost to overgrazing, contaminated runoff from agriculture, and heavy recreational use.

ABC and its partners in the North American Bird Conservation Initiative (NABCI) are working to integrate bird conservation priorities for waterbirds, landbirds, and shorebirds including the Wilson’s Phalarope into programs such as the Joint Venture network, with funding support under the North American Wetland Management Act. ABC has also worked with a wide variety of organizations and private landowners throughout Montana to restore and protect over 1,700 acres of wetlands where Wilson’s Phalaropes breed.