Argentina, Bolivia, Brazil, Chile (B), Colombia, Falkland Islands (Malvinas), French Guiana, Guyana, Panama, Paraguay, South Georgia and the South Sandwich Islands, Suriname, Uruguay (B), Venezuela.
Population
Estimated population is 25,000 - 100,000 (2010).
Buff-necked Ibis (Theristicus caudatus) [XC272695]
by Marcelo Villegas from Lake south of Santa Laura pass, Salta, Argentina (call)
Buff-necked Ibis (Theristicus caudatus) [XC680722]
by JAYRSON ARAUJO DE OLIVEIRA from Reserva do Setor S\u00edtio de Recreio Cara\u00edbas-Goi\u00e2nia, Goi\u00e1s, Brazil (call, song)
Subspecies
Forms superspecies with Black-faced Ibis (Theristicus melanopis), which was formerly considered a subspecies of this species.
The following 2 subspecies are recognised:
caudatus (Boddaert, 1783) - Colombia and Venezuela to French Guiana, south to Mato Grosso, Brazil.
hyperorius Todd, 1948 - Eastern Bolivia to south-eastern Brazil, Paraguay, northern Argentina and Uruguay.