List of Rheiformes by population

This is a list of Rheiformes species by global population. While numbers are estimates, they have been made by the experts in their fields. For more information on how these estimates were ascertained, see Wikipedia's articles on population biology and population ecology.

The IOC World Bird List (version 15.1) recognizes 2 species of Rheiformes. As of December 2025, IUCN/BirdLife International have assessed all members, and 1/2 (50%) of species have population estimates. This list follows IUCN classifications for species names. Where IUCN classifications differ from other ornithological authorities, alternative names are noted.

Species by global population

Common name

Binomial name

Population

Status

Trend

Notes

Image

Greater rhea

Rhea americana

unknown

Rhea_americana_qtl2.jpg

Lesser rhea (Darwin's rhea)

Rhea pennata

1,000-2,499

Values are preliminary estimate for number of mature individuals.

Rhea_pennata_pennata_(6).JPG

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