Both the Greater and Lesser rheas are declining in their natural South American habitats. Research into the biology and behavior of the Greater Rhea may help prevent this trend in rheas and other ratites.
Behavioral research in the wild has concentrated on specific isolated populations and single subspecies. Future research much broaden the scope of observed populations and compare more of the five distinct subspecies before generalizations are made.
Because the rhea sometimes is kept in captivity, primarily as a commercial product, there is a good amount of literature on its physiology and reproduction. However, few such studies have been conducted in the wild. The Greater Rhea offers a particularly interesting and unusual mating system that has been the subject of a few observational field studies which have uncovered some of its structure, and further behavioral study coupled with genetic analysis of parentage and relatedness will help fill in the picture of the costs and benefits of the rhea's reproductive peculiarities.