The 31-hectare (76-acre) Humedal del Río Lluta [Lluta River Wetland] in northernmost Chile is a Municipal Natural Reserve as well as a federal Natural Sanctuary. The wetland is a WHSRN Site of Regional Importance, supporting more than 20,000 shorebirds including 1.4% of the Sanderling (Calidris alba) and 1.8% of the Whimbrel (Numenius phaeopus) populations wintering in the area. It also hosts two South American endemic shorebird species: Peruvian Thick-knee (Burhinus superciliaris) and White-backed Stilt (Himantopus melanurus).