The willet (Tringa semipalmata), formerly in the monotypic genus Catoptrophorus as Catoptrophorus semipalmatus, is a large shorebird in the family Scolopacidae. It is a relatively large and robust sandpiper, and is the largest of the species called "shanks" in the genus Tringa. Its closest relative is the lesser yellowlegs, a much smaller bird with a very different appearance apart from the fine, clear, and dense pattern of the neck, which both species show in breeding plumage. It breeds in North America and the West Indies and winters in southern North America, Central America, the West Indies and South America.
The Willet is widespread in the Western Hemisphere including the West Indies, where it is a year-round resident in The Bahamas, Greater Antilles, and Cayman Islands, particularly from August to November when breeding resident populations are joined by migrants from North America (Raffaele and others 1998). It is observed mostly from August to April on Puerto Rico (Biaggi 1997), regularly in the municipality of Cabo Rojo (Oberle 2018). It also occurs on Vieques, where it is a rare passage migrant during fall, late winter, and spring, and is extremely rare in summer (Gemmill 2015). This species habitat includes mostly tidal fl ats, edges of both saltwater and freshwater bodies (Raffaele and others 1998), mudfl ats, mangroves (Oberle 2018), and beaches (Biaggi 1997). The atlas fieldwork yielded a total of 23 records within 15 hexagons or 3 percent of the 479 total hexagons with all records occurring in coastal hexagons (see map). Of the 15 hexagons where this species was found, breeding met the atlas definition of confirmed in 20 percent (three) of the hexagons, probable in 7 percent (one), and possible in 27 percent (four), while the species was observed in 47 percent (seven) of the hexagons but without evidence of breeding (see map). Willet distribution. The map shows the highest breeding code by hexagon and overlaying the ecological life zones in Puerto Rico. Note: percentages may not total 100 due to rounding. 111Willet/Playero Aliblanco
The Willets nest is a slightly lined concavity in the sand, sometimes with dried weeds in the center (Biaggi 1997, Raffaele and others 1998). Previously published reports indicate that breeding occurs from April to July (Raffaele and others 1998). Atlas results show that this species breeding season extends mostly from May to August and to a lesser extent in February, with the most breeding activity during July (see chart). Results show that this species breeds within the subtropical dry forest life zone (100 percent of the hexagons) on the south coast of Puerto Rico (see table and map).
The current global population trend of the Willet is described as stable, although some populations have unknown trends (Wetlands International 2012). This species is currently listed as a species of least concern by the IUCN (BirdLife International 2016). Locally, this species is not listed in any of the threatened categories of PRDNER and USFWS. In Puerto Rico, the Willet has a protected habitat in land of 20 percent or 38 km2 of the total area covered by the hexagons where evidence of breeding was found for this species (191 km2).