Rhea americana Distribution: Range Expansion and Introductions of America’s Largest Bird

Abstract

Species distribution is a good predictor of several important traits, including threat status. Additionally, species expanding out of their original range can become invasive and this trend must be evaluated objectively. The greater rhea (Rhea americana) is a flightless large-sized avian species that thrives on open landscapes of South America. The species has been affected by the conversion of their savanna habitat into cropland and pastures, as well as benefited from forest conversion into fields at neighboring ecoregions. I propose to evaluate those range expansions, contractions and extirpations, as well as to depict the current species distribution. Here I show that greater rheas have expanded their range out of the “dry lands diagonal” into degraded portions of forested ecosystems—more extensively on the Amazon Forest—while persisting in human-altered landscapes of their historical range. This suggests that the species is faring well regarding conservation, which does not justify its current status at IUCN. Additionally, the potential ecological interactions of the species in newly colonized environments must be investigated. The faunal savanization undergoing in the Neotropics accounts on many new ecological interactions, of which greater rheas are a relevant part. Future actions of management may improve the species conservation profile.