Like other phalaropes, Wilson’s Phalarope is thoroughly at home landing and feeding in water. However, as the most terrestrial of the phalarope species, it spends most of its time on land in both summer and winter.

Characteristic of the bird are its needle-thin, medium-long, straight black bill, pot-bellied look and long neck; see Fig. 1, Fig. 17.

Wilson’s Phalarope’s frenetic behavior draws attention when it feeds among other, more sedate shorebirds. It often stretches its neck and chases about in shallow water, picking tiny food items off the water surface or vegetation leaves; see Fig. 5, Fig. 15, Fig. 22.

Juvenile legs are pale—yellow, pale green or pinkish. Once the bird molts to winter (basic) plumage, leg color may darken. Winter birds may have pale or dark legs, depending on age. By spring, most have dark legs; see Fig. 3, Fig. 7, Fig. 12, Fig. 17.

Winter (basic) plumage is pale gray on the back (mantle). Each back (mantle) feather has a very thin, pale margin. The underparts are mostly white, with a gray wash and faint gray marks on the neck, upper chest and flanks. A pale gray line through the eye curves downward along the neck. There is a bold white supercilium (eyebrow); see Fig 1, Fig. 2, Fig. 3, Fig. 4.

By late February, many Wilson’s Phalaropes begin the molt to spring (alternate) plumage; see Fig. 4, Fig. 5, Fig. 9.

In breeding (alternate) plumage, both sexes have a white stripe up the nape; see Fig. 6.

Female Wilson’s Phalarope in breeding (alternate) plumage is among the showiest and most colorful of shorebirds. It has a pale blue crown, bold black eyelines connecting to luminous rufous-maroon stripes down the sides of the neck, gray and maroon alternating stripes on the back (mantle), peach-colored wash on the sides and front of the neck. The legs and bill are black; see Fig. 6; Fig. 7, Fig. 8, Fig. 10, Fig. 26.

Male Wilson’s Phalarope in breeding (alternate) plumage is Iess showy: the crown is darker gray, the eyelines paler and the rufous-maroon color down the sides of the neck less extensive. There are only a few rufous feathers on the back; see Fig. 12.

By midsummer, alternate plumage begins to be replaced by winter (basic) plumage; see Fig. 15.

The newly hatched downy chick is precocial—it can run about or swim and feed itself soon after emerging from the egg; see Fig. 14.

Chicks replace natal down with juvenile plumage within a few weeks.

Juvenile back (mantle) plumage consists of dark brown feathers neatly edged with pale buff margins; this gives the back of the bird the characteristic scalloped look of most juvenile shorebirds. A dark, brown-streaked cap, white supercilium (eyebrow) that flares toward the back of the head, a gray eyeline and white cheeks with a blush of buff along the sides of the neck characterize this stage. The legs are yellowish, pale green or pinkish; see Fig. 17.

As summer progresses into fall, juvenile back (mantle) feather margins become worn and frayed. Fresh winter (basic) feathers begin to grow in; see Fig. 18.

In flight, Wilson’s Phalarope displays a pale tail and gray or gray-brown upper wings. The body is torpedo-shaped and wingtips are slightly rounded; see Fig. 10, Fig. 11. In all plumages, the rump is white. Juvenile tail feathers have subterminal grey margins; see Fig. 19.

Wilson’s Plover breeds across most of the northern tier of states in the United States and in southwestern Canada. The majority of the breeding population nests in the western half of the continent, and also around the Great Lakes. Sporadic nesting has been recorded in southeastern Canada (New Brunswick, Nova Scotia) and northeastern United States (Massachusetts, New York).

Wilson’s Plover’s nesting habitat consists primarily of interior North American wetlands and marshes. In Massachusetts, nesting has occurred at Plum Island, Essex County, and Monomoy National Wildlife Refuge, Chatham.

Nests are on the ground, usually in dense vegetation. Wilson’s Phalarope’s normal clutch size is four eggs. Eggs are extensively splotched with dark brown and green; see Fig. 13.

On the breeding grounds, females compete among one another for male selection. Once pairs have formed, the female lays a clutch of eggs, then often abandons the nest and continues to court additional males.

The male alone incubates the eggs and spends a short time tending to the chicks by brooding and guarding against predators.

Female Wilson’s Phalaropes depart the nesting grounds around mid-June, followed about two weeks later by males. Juveniles follow somewhat later.

For several weeks in the summer, Wilson’s Phalaropes that breed in the western half of North America congregate in vast numbers in staging areas in order to fatten up and molt into winter (basic) plumage; see Fig. 16. Favored staging areas are saline or alkaline lakes and wetlands such as Old Wives Lake, Saskatchewan; Great Salt Lake, UT; Lake Abert, OR; Mono Lake, CA; and Carson Sink, NV. Wilson’s Phalarope is one of the few shorebird species that molts nearly completely at northern staging locations prior to departing for South American wintering grounds.

During fall migration season, adult phalaropes depart at night in a southwesterly direction, passing over the Pacific Ocean en route to the central South American coast. At this season, adult phalaropes are scarce in Central America and northern South America.

Prior to departure for South America, adults put on weight at a prodigious rate, at times gaining so much weight that they are temporarily unable to take flight.

Juveniles migrate at a more leisurely pace through the central United States and into Mexico, Central America and northern South America. Birds nesting in eastern states and provinces migrate along paths similar to other migratory shorebirds and arrive in South America on a schedule similar to western birds.

Most Wilson’s Phalaropes winter in central-western and southern South America, all the way to Tierra del Fuego in Chile and Argentina. Their preferred habitat consists of mudflats of saline, alkaline and freshwater marshes, lakes and ponds of the high Andes.

Spring migration is largely overland through Central America and central North America, with the majority of migrants passing through prairie potholes such as Cheyenne Bottoms, KS. By May, some breeding-plumaged adults reach latitudes in the northeastern United States. Food for nesting birds and their nestlings consists of various classes of insects (flies, bugs, beetles) as well as some crustaceans and aquatic plants.

During migration and at wintering spots, major diet items are brine shrimp, brine flies and other aquatic invertebrates.

The frenetic feeding style of this species is characterized by birds twirling in the water to stir up aquatic insects or individuals running through the grass and jabbing at insects on plant leaves; see Fig 1, Fig. 5.

Wilson’s Phalarope (WIPH) is larger and longer-billed than Red-necked Phalarope (RNPH). For comparison, see Fig. 20.

Note the following:

• Wilson’s and Red-necked Phalaropes have needle-thin bills, but Wilson’s bill is usually much longer.
• In breeding (alternate) plumage, Wilson’s female has a pale blue-gray cap; the male’s cap is somewhat darker. Both sexes of Wilson’s have a white face with a bold dark line through the eye. Red-necked is dark-faced and dark-capped.
• In breeding (alternate) plumage, Wilson’s has a pale chin, face and throat. Red-necked’s white chin and throat contrast strongly with its dark head and neck.
• Wilson’s has maroon and rufous on the sides of the neck; the female has a white stripe up the nape. Red-necked is maroon and rufous on the sides and rear of the neck and nape.
• In winter (basic) and juvenile plumage, Wilson’s Phalarope acquires plain gray upperparts. Red-necked’s plumage is darker, contrasting sharply with white stripes on the back (mantle); see Fig. 20.
• In winter (basic) and juvenile plumage, Red-necked has more of a contrasting head and facial pattern (black-and-white) than Wilson’s.
• In flight, in all plumages, Wilson’s has plain gray upper wings with very faint white stripes. Red-necked displays bold white wing-stripes.

Wilson’s Phalarope (WIPH) and Red Phalarope (REPH) are similar in size, but Wilson’s is longer-necked and longer-legged. For comparison, see Fig. 21.

Note the following:

• In breeding (alternate) plumage, Red Phalarope is unmistakable: It has a rufous-maroon body with a gray back, white face and yellow bill.
• In winter (basic) and juvenile plumage, the two phalaropes are somewhat more alike. Wilson’s bill is long and needle-like, whereas Red has a shorter, thicker, blunter bill, often with a hint of yellow or orange at the base.
• In winter (basic) and juvenile plumage, Red Phalarope’s eyeline and cap are blackish and contrast strongly with the white face and sides of the neck. Wilson’s eyeline and cap are gray with less contrast.
• In flight, Red Phalarope displays broad white wing-stripes compared to the plain gray upper wings of Wilson’s.

Wilson’s Phalarope (WIPH) is considerably larger and taller than Semipalmated Sandpiper (SESA). The phalarope has a long, straight, needle-shaped bill compared to the thicker, stubbier bill of the sandpiper. Juvenile Wilson’s Phalarope’s legs are pale (yellow, greenish or pinkish), whereas Semipalmated Sandpiper had dark legs; see Fig. 22.

Wilson’s Phalarope (WIPH) and Stilt Sandpiper (STSA) are nearly identical in size. Note the difference in bill shape: straight and needle-shaped in the phalarope; long, thick and downturned in Stilt Sandpiper; see Fig. 23.

Note also the following:

• Breeding (alternate) plumaged Wilson’s Phalarope has bold rufous and black stripes up the sides of the neck and a black eyeline. Breeding plumaged Stilt Sandpiper has rufous cheeks and eyelines as well as rufous in the crown.
• Breeding (alternate) plumaged Wilson’s Phalarope’s breast and belly are white with some peach-colored suffusion on the flanks and the neck. Stilt Sandpiper in alternate plumage is heavily barred with brown marks on the neck, breast and belly.
• In winter (basic) plumage, Wilson’s Phalarope has pale, evenly gray back (mantle) feathers with pale narrow margins. Stilt Sandpiper’s mantle feathers in winter (basic) plumage are gray brown with darker centers.
• Juvenile Wilson’s Phalarope has a scalloped look to the back (mantle) due to dark brown feathers with buffy margins. Stilt Sandpiper juvenile has a similar mantle pattern, but the feather margins are neutral or white, not buffy. Bill shape is most helpful in this case.
• Stilt Sandpiper’s feeding pattern often is to stand in one spot and probe up and down in belly-deep water. Wilson’s Phalarope’s feeding behavior is frequently much more frenetic as the bird darts about, stretching its neck in different directions, looking to pluck prey from vegetation or the water surface.

Wilson’s Phalarope (WIPH) is similar to Lesser Yellowlegs (LEYE) but is smaller and much shorter-legged; see Fig. 24.

Note the following:

• In breeding (alternate) plumage, Wilson’s Phalarope female is unmistakable with rufous-maroon stripes down the sides of the neck and maroon and gray stripes on the back (mantle).
• Male Wilson’s Phalarope has breeding plumage similar to the female, but the back is scalloped instead of striped, maroon-and-gray.
• In breeding (alternate) plumage, Lesser Yellowlegs is spotted and checkered on the back (mantle).
• Wilson’s Phalarope has a white belly and peach-tinted flanks. Lesser Yellowlegs is barred and spotted extensively on the belly, breast and especially the flanks.
• Juvenile Wilson’s Phalarope has scalloped, dark brown feathers with buffy margins on the back (mantle). Lesser Yellowlegs juvenile is spotted on the mantle.
• Winter (basic) plumage of Wilson’s Phalarope is unpatterned gray on the back (mantle) and white on the underparts. Lesser yellowlegs’ winter mantle plumage is gray and spotted.
• Compared to Lesser Yellowlegs, Wilson’s Phalarope’s legs are short. They may be yellow, but as the bird matures, they become darker.
• Wilson’s Phalarope has a pot-bellied or full-chested appearance, whereas Lesser Yellowlegs looks sleek.
• Wilson’s Phalarope’s bill is much thinner than that of Lesser Yellowlegs.
• Watch for the frenetic feeding style of Wilson’s Phalarope, usually quite different from the staid behavior of Lesser Yellowlegs.

Wilson’s Phalarope (WIPH) is much smaller than Greater Yellowlegs (GRYE); for comparison, see Fig. 25.

Note the following:

• In breeding (alternate) plumage, Wilson’s Phalarope female is unmistakable with rufous-maroon stripes down the sides of the neck and maroon and gray stripes on the back (mantle); see Fig. 26.
• Male Wilson’s Phalarope has breeding plumage similar to the female, but the back is scalloped instead of striped, maroon-and-gray.
• In breeding (alternate) plumage, Greater Yellowlegs acquires contrasting black-centered feathers on the mantle and heavier streaking on the neck and head.
• Wilson’s Phalarope’s bill is needle-thin and proportionally shorter, whereas Greater Yellowlegs’ bill is thicker, longer and often slightly upturned.
• Wilson’s Phalarope juvenile legs are yellow, but as the bird matures, they become darker.