Bird of the Week: Wilson’s Phalarope

Wilson’s Phalarope
Phalaropus tricolor

Compiled and written by Lindsey Hernandez
Photo by Tony Williams

A slender, energetic shorebird, Wilson’s Phalarope can be seen through most of Texas during their spring and summer migration from South America to their breeding grounds in the Northwestern United States and Canada. They can be easily identified by their size and dashing rusted brown plumage about the neck. However, the brightest plumage will not be seen on the male but the female. And the switching of the feathers is not the only gender norm this bird swaps.

Wilson’s Phalarope exhibits an unusual form of polyandry, where females mate with multiple males, who then take on the primary role of incubating eggs and caring for the young. The females, more colorful and larger than the males, engage in aggressive courtship behaviors and, once they lay their eggs, leave the males to tend to the nests. And of course, this role reversal can also be seen in their plumage: breeding females display striking cinnamon highlights and a dark line over their eyes, making them more vibrant compared to the duller males.  This polyandrous system allows females to seek out additional mates while the males raise the young.

Despite their relatively small size, Wilson’s Phalaropes undertake a remarkable migration, traveling from their breeding grounds in the northwestern United States and Canada to wintering grounds on high mountain lakes in the Andes.

In Texas, sightings are common during these migratory periods, although breeding records within the state are sparse. The Wilson’s Phalarope’s adaptation to both saline and freshwater environments is a testament to its versatility. During migration, they frequent prairie lakes, fresh marshes, mudflats, and salt marshes. They are particularly fond of habitats that offer abundant food sources, such as midges and shrimp, which they capture using their distinctive spinning technique.

While foraging in the water, the bird will swim in circles to create a whirlpool that sucks up food items to the surface of the water. Once a whirlpool has been created, the phalarope will reach down with its beak into the center and pluck out its meal.  This unique feeding behavior not only sustains them but also helps them double their body weight in preparation for the long journey ahead. Sometimes, they consume so much food that they become too heavy to fly, which makes it possible for researchers to catch them by hand.

Other techniques include chasing and pecking prey from the surface of mud or water, standing still and stabbing at passing flies, and probing inside mud.

In addition to their polyandry and unusual feeding technique, Wilson’s Phalaropes are distinct in their breeding and migratory behaviors. Unlike most shorebirds, they molt at resting sites along their migration route rather than at their breeding or wintering grounds. This molt typically occurs while the birds are feeding voraciously on the saline lakes.

Resources: All About Birds and The Texas Breeding Bird Atlas.