Comments: Marshes, tidal mudflats, beaches, lake margins, mangroves, tidal channels, river mouths, coastal lagoons, sandy or rocky shores, and, less frequently, open grassland (AOU 1983, Stiles and Skutch 1989). Nests along marshy lake margins in western North America, salt marshes in eastern North America. Nests on the ground in open places, coastal marshes, beaches, or islands; and inland in wet grassland by lakes, or short grass or bare ground by water.
Breeding requires large expanses of short, sparse grasslands for nesting and foraging, and wetland complexes for foraging (Stewart 1975; Weber 1978; Kantrud and Stewart 1984; Ryan and Renken 1987; Colwell and Oring 1988a, 1990; Kantrud and Higgins 1992; Prescott et al. 1995). In both upland and wetland habitats, adults with broods use somewhat taller, denser grass cover than do breeding pairs during nesting (Ryan and Renken 1987). In North Dakota, uplands used by Willets had a thinner litter layer than surrounding areas (Renken 1983). They often nest near a conspicuous object such as a piece of wood, dried cattle dung, or a stone (Higgins et al. 1979, Kantrud and Higgins 1992).
Prefer native grass to tame vegetation (Stewart 1975, Ryan and Renken 1987, Kantrud and Higgins 1992). They prefer pastures that are idle during the nesting season, and to a lesser extent actively grazed pasture, to other land-use types (Higgins et al. 1979, Ryan and Renken 1987, Kantrud and Higgins 1992). Although tilled lands usually are avoided (Weber 1978), nests have been reported in hayland and cropland, including small-grain, flax, and stubble fields (Higgins et al. 1979, Kantrud and Higgins 1992). In North Dakota, pairs nesting in native vegetation had higher hatching success than pairs nesting in cultivated fields (Higgins et al. 1979). In the prairie and aspen parkland regions of Alberta, mean number of birds/site was nonstatistically compared among several habitats (Prescott et al. 1995, Prescott 1997). In prairie, were most abundant in native mixed-grass, followed by coulee, upland shrub, planted cropland, and hayland (Prescott 1997). Coulee was defined as a valley containing an ephemeral creek or seepage that may contain other, undescribed, habitat types. Hayland was planted to grasses (species not given) or alfalfa (MEDICAGO SATIVA). In the uplands of aspen parkland, were most abundant in deferred native pastures grazed after 15 July, followed by idle native grassland, continuously grazed native parkland, and tame dense nesting cover (Prescott et al. 1995). They were not found in tame pasture, deferred tame pasture, idle tame uplands, idle tame grasslands, continuously grazed native grasslands, idle parkland, or native dense nesting cover.
In wetlands, avoid dense, emergent vegetation, preferring shallow-water areas with short, sparse shoreline vegetation (Ryan and Renken 1987, Colwell and Oring 1988a, Eldridge in prep.). Suitable wetlands range in salinity from fresh to saline, and vary widely in size and permanence (Stewart 1975, Kantrud and Stewart 1984, Ryan and Renken 1987, Prescott et al. 1995, Eldridge in prep.). In North Dakota, were more common in alkali or permanent wetlands than in temporary, seasonal, or semipermanent wetlands (D. H. Johnson et al., unpubl. data). Shifts in wetland use occur seasonally and during climatic extremes (Ryan and Renken 1987; Gratto-Trevor, in press). Semipermanent wetlands were used most often, but ephemeral, temporary, seasonal, and alkali ponds were preferred relative to their availability (Ryan and Renken 1987). Semipermanent wetlands were used later in the summer than other wetland types. Semipermanent and permanent wetlands were used during drought years.
