- Tringa semipalmata
33-41 cm length, 60-70 cm wingspan, 173-375 g weight.
- Dark gray upperparts
- Light underparts
- White tail with a dark band at the end
- Wings with grey inner wing, striking black and white stripes on outer wing
- Gray legs
- Long, straight, dark and stout bill
Sexes alike. Adults in breeding plumage can usually be identified to subspecies in the field, but winter birds much less readily.
North America, some wintering south to Chile and Brazil. All populations are migratory, though present all year on the Atlantic and Gulf Coasts, where breeding T. s. semipalmata move out to be replaced in winter by non-breeding T. s. inornata.
- T. s. semipalmata breeds in coastal marshes on the east coast of North America from southeastern Canada to Gulf Coast and the West Indies; winters from the Caribbean south to southern Brazil.
- Darker overall in breeding plumage, with breast heavily barred. On average, 10% smaller, but much overlap in size.
- T. s. inornata breeds in the interior (south-central Canada and western USA - Nebraska and Colorado); winters mainly on the west coast from Washington south to Peru (rarely to northern Chile), but also some on the east coast from New Jersey southwards.
- Paler overall in breeding plumage, with breast only lightly barred. On average, 10% larger, but much overlap in size.
Breeds in freshwater marsh habitat, outside of breeding found on tidal beaches and mudflats.
Colonial breeders, the ground nest is well hidden in short grass.
The diet includes insects, crustaceans and marine worms, and some plant material. They forage on mudflats or in shallow water.
Rather noisy, giving loud “klip” or “kleep” in alarm and a harsh “wee-wee-wee” in flight, but is best known for ringing "Pill-will-willet" in display on breeding grounds.
- Clements, J. F., T. S. Schulenberg, M. J. Iliff, D. Roberson, T. A. Fredericks, B. L. Sullivan, and C. L. Wood. 2018. The eBird/Clements checklist of birds of the world: v2018. Downloaded from http://www.birds.cornell.edu/clementschecklist/download/
- Christidis et al. 2018. The Howard and Moore Complete Checklist of the Birds of the World, version 4.1 (Downloadable checklist). Accessed from https://www.howardandmoore.org.
- Sibley, CG and BL Monroe. 1996. Birds of the World, on diskette, Windows version 2.0. Charles G. Sibley, Santa Rosa, CA, USA.
- Gill, F & D Donsker (Eds). 2018. IOC World Bird List (v8.2). doi : 10.14344/IOC.ML.8.2. Available at http://www.worldbirdnames.org/
- Sibley Guides: Guessing the next ten bird splits
- Birdforum thread discussing taxonomy of the species
- Birdforum thread discussing the identification of Eastern from Western Willet
- Lowther, P. E., H. D. Douglas III, and C. L. Gratto-Trevor (2001). Willet (Tringa semipalmata), version 2.0. In The Birds of North America (A. F. Poole and F. B. Gill, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bna.579
- Van Gils, J., Wiersma, P. & Kirwan, G.M. (2018). Willet (Tringa semipalmata). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from https://www.hbw.com/node/53916 on 22 October 2018).
- BirdForum Opus contributors. (2021) Willet. In: BirdForum, the forum for wild birds and birding. Retrieved 4 August 2021 from https://www.birdforum.net/wiki/Willet