Rheiformes is an order that contains the family
Rheidae (rheas).[3] It is in the infraclass
Paleognathae, which contains all
ratites. Extant members are found in South America. While the IOC World Bird List and the Clements Checklist categorise Rheiformes as its own order,[3][4] the BirdLife Data Zone includes rheas, along with
ostriches,
tinamous,
cassowaries,
emu, and
kiwis, in the order
Struthioniformes.[5] Of the two extant species of rheas recognized by the
IUCN Red List, as of 2022[update], Rhea americana is listed as near threatened,[6] while Rhea pennata is listed as least concern.[7] From 2014 to 2022, the
IUCN recognised Rhea tarapacensis as a separate species, and listed it as near threatened in its last assessment in 2020;[8] in 2022, it was again recognised as a subspecies of R. pennata.[7]: Taxonomy
References
^Kirwan, Guy M.; Korthals, Arne; Hodes, Carly E. (2 April 2021). "Greater Rhea (Rhea americana), version 2.0". In Keeney, B. K. (ed.). Birds of the World.
Ithaca, New York, United States:
Cornell Lab of Ornithology.
doi:
10.2173/bow.grerhe1.02.
^
abGill, Frank; Donsker, David; Rasmussen, Pamela, eds. (11 August 2022).
"Ratites: Ostriches to tinamous". IOC World Bird List (version 12.2 ed.). Retrieved 29 November 2022.