Vocalisations of the Greater Rhea (Rhea americana): an allegedly silent ratite

Our current knowledge of the vocal behaviour of Palaeognathae is limited, although it may increase our understanding of the evolution of avian vocal behaviour. The Greater Rhea (Rhea americana) has a complex syrinx, and males produce guttural sounds during the courtship display, which makes this species an interesting model to study vocal behaviour in ratites. We recorded a group of Greater Rheas living in semi-captive conditions at the zoo of the UFMT for eight days. A total of 749 booming calls were detected. The vocal activity of the Greater Rhea was maximum during the first four hours after sunrise, with a second peak before sunset. The species showed nocturnal vocal activity, as also found in a recent study on a diurnal tinamou. The number of vocalising birds during the recording period was unknown, and our data were collected during a restricted time window. Our results suggest that acoustic communication and nocturnal activity of the species might be more relevant than previously described. Passive acoustic monitoring may have further implications for the continued study of vocal activity in ratites. Further research should examine whether the vocal behaviour and nocturnal vocal activity of the Greater Rhea are also important in wild individuals.

Automated summary

The vocal behavior of the Greater Rhea, a type of Palaeognathae, shows unique characteristics such as peak vocal activity in the first four hours after sunrise and before sunset, as well as nocturnal vocal activity. The study suggests that acoustic communication and nocturnal activity of the species may be more significant than previously described. Further research is needed to investigate the importance of vocal behavior and nocturnal vocal activity in wild individuals.