Habitat
Wilson's Phalaropes breed in wetlands, upland shrubby areas, marshes, and roadside ditches. During migration, most individuals stop over at saline lakes in western North America, as well as coastal marshes and sewage ponds. Their winter habitat consists of high Andean salt lakes as well as wetlands in southern South America.Back to top
Food
Wilson's Phalaropes mainly eat small aquatic invertebrates such as midges and shrimp. While foraging in the water, they often spin in circles to create a whirlpool that sucks up food items to the surface of the water. 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.Back to top
Nesting
Nest Placement
The female usually chooses a site around the edge of a wetland or in surrounding upland vegetation.
Nest Description
The female lays her eggs in nothing more than a scrape on the ground. Later, the male tidies the scrape and arranges the surrounding vegetation to hide the nest.
Nesting Facts
| Egg Length: | 1.3-1.4 in (3.2-3.5 cm) |
| Egg Width: | 0.9-0.9 in (2.3-2.4 cm) |
| Incubation Period: | 18-27 days |
| Egg Description: | Buffy, covered with brown blotches. |
| Condition at Hatching: | Fully feathered and eyes open, able to feed themselves. |
Behavior
Phalaropes are unusual in that their mating system is polyandrous, meaning females usually mate with multiple males. Females vie for males with aggressive postures involving jutting the head back and forth, sometimes breaking into fights. Once the female acquires a mate, she begins to use courtship displays involving bowing and upright postures to initiate copulation. Soon after laying a complete clutch, the female usually abandons the male to seek out another male to mate with. Wilson's Phalaropes are very social throughout the year. They nest relatively close together in small, loose colonies, and during migration they travel in large flocks. Predators include garter snakes, gulls, crows, blackbirds, skunks, ground squirrels, and racoons.Back to top
Conservation
Wilson’s Phalarope numbers have remained level or declined slightly since 1966 (less than 1% per year), according to the North American Breeding Survey. A 2012 assessment estimated their population at 1.5 million breeding individuals, although it noted a lack of data and based this estimate on a 2006 study. Wilson’s Phalaropes breed across the Great Plains and intermountain West, and their numbers dropped sharply in the early twentieth century as wetlands in these regions were altered. They are still dependent on wetland habitat, water quality, and the availability of surface water. On migration they stage in huge numbers at hypersaline lakes such as Mono Lake and the Salton Sea. Because so many birds congregate, changes to these areas including water diversion and reclamation could have serious repercussions.Back to top
Credits
Andres, B. A., P. A. Smith, R. I. G. Morrison, C. L. Gratto-Trevor, S. C. Brown, and C. A. Friis (2012). Population estimates of North American shorebirds, 2012. Wader Study Group Bulletin 119:178–194.
Colwell, M. A. and Joseph R. Jehl Jr. (1994). Wilson's Phalarope (Phalaropus tricolor), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.
Dunne, P. (2006). Pete Dunne's essential field guide companion. Houghton Mifflin Harcourt, New York, USA.
Ehrlich, P. R., D. S. Dobkin, and D. Wheye (1988). The Birder's Handbook. A Field Guide to the Natural History of North American Birds, Including All Species That Regularly Breed North of Mexico. Simon and Schuster Inc., New York, NY, USA.
North American Bird Conservation Initiative. (2014). The State of the Birds 2014 Report. US Department of Interior, Washington, DC, USA.
Sauer, J. R., J. E. Hines, J. E. Fallon, K. L. Pardieck, Jr. Ziolkowski, D. J. and W. A. Link. The North American Breeding Bird Survey, results and analysis 1966-2013 (Version 1.30.15). USGS Patuxent Wildlife Research Center (2014b). Available from http://www.mbr-pwrc.usgs.gov/bbs/.
Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, NY, USA.