The diademed sandpiper-plover or diademed plover (Phegornis mitchellii) is a Near Threatened species of bird in subfamily Charadriinae of family Charadriidae. It is found in Argentina, Bolivia, Chile, and Peru. Taxonomy and systematics The diademed sandpiper-plover is the only member of its genus and has no subspecies. The species has at times been thought to belong to family Scolopacidae (the sandpipers) but genetic data place it firmly with other plovers in family Charadriidae. It appears to be most closely related to several Australian and New Zealand plovers of genera Elseyornis, Peltohyas, Anarhynchus, and Pedionomus. Description The diademed sandpiper-plover is long and weighs . The sexes are alike. Their bill is black and slightly decurved. Their legs and feet are orange. The adult's face is black with a wide white supercilium than extends around the back of the head. Their crown is black, their nape bright rufous, most of their upperparts dark brownish gray, and their rump and uppertail coverts are black. The tail is black with white tips to the feathers. Their throat is white, their chest, belly, and flanks are barred black and white, and their vent and undertail coverts are unmarked white. Juveniles are much duller than adults. Their upperparts are mostly brownish gray with cinnamon speckles and bars. Their supercilium is grayish and their nape is washed with cinnamon or rufous. Distribution and habitat The diademed sandpiper-plover is found in the Andes from central Peru's Department of Junín south through western Bolivia to central Chile and south-central Argentina. It is a habitat specialist found almost entirely in peatlands and bogs between the frost line and snow line. The habitat is "characterized by a network of grassy banks interspersed with long streams and vernal pools". In elevation it ranges between in Peru though in the southern part of its range it is found as low as . Behavior The diademed sandpiper-plover is almost always seen alone or in pairs. It is not known if this is true social monogamy, territoriality, a function of its sparse population, or because of lack of enough study. Migration The diademed sandpiper-plover is an elevational migrant in the southern part of its range. Those nesting in the highest areas move to lower ones in March and return in October. The southernmost population is thought to be at least partially north-south migratory as well. Feeding The diademed sandpiper-plover typically forages alone or in pairs,