Abstract
In a private wildlife research facility and rhea farm of Argentina, artificially incubated eggs of putative hybrid origin between the Greater Rhea (Rhea americana) and the Lesser Rhea (Rhea pennata) hatched and gave birth to healthy chicks. Molecular genotyping by the analysis of mitochondrial Cytochrome b (Cyt b) and nuclear Chromo- Helicase DNA binding (CHD1) gene sequences confirmed the hybrid origin of these chicks which were molecularly sexed as females. The possibility of hybridisation argues for careful management of captive populations of these species, especially if individuals are to be released in the wild for conservation purposes.