The Buff-necked Ibis, Theristicus caudatus, also known as the White-throated Ibis, is a medium-sized, approximately 76cm long, South American ibis. It has a buffish neck, black bill, grey upperparts, reddish legs, partly white wing, and is black below. Both sexes are similar.

Its appearance resembles the Black-faced Ibis, distinguished by its white wings and for having less extent of buffish breast than the latter species.

The Buff-necked Ibis lives in the woodlands, marshes, savanna, lakes and open forests of the eastern regions of South America, from Colombia to Uruguay and northern parts of Argentina. Its diet consists mainly of insects, spiders, frogs, reptiles, snails, invertebrates and small mammals found in soft soils. The female usually lays between two to four eggs in a platform nest on trees, made from twigs and branches.

Widespread throughout its large habitat range and with an estimated population size of 25,000 to 100,000 birds, the Buff-necked Ibis is evaluated as Least Concern on the IUCN Red List of threatened Species.