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

ABSTRACT

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.

KEYWORDS:

• Boom
• captive
• Neotropics
• nocturnal
• Palaeognathae
• Rheida

Acknowledgements

We thank Prof. Marinêz Isaac Marques for her constant support and help and to Ana Silvia Tissiani and Filipe Ferreira de Deus for their technical assistance. We also thank the whole zoo staff, and especially the zoo coordinator, Prof. Sandra Helena Ramiro Côrrea, for permission to conduct our research at the zoo. We wish to thank two anonymous reviewers for their comments that helped to improve the manuscript. This study is part of the biodiversity monitoring project Sounds of the Pantanal–The Pantanal Automated Acoustic Biodiversity Monitoring of INAU, Cuiabá, Mato Grosso, Brazil, which was conducted under SISBIO permit no. 39095 (KLS). We are also grateful to the Cornell Lab of Ornithology for the license for Raven Pro: Interactive Sound Analysis Software.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data accessibility

Raw data employed for creating graphs and data analyses can be found at: 10.6084/m9.figshare.12789152

Supplementary material

Supplemental data for this article can be accessed here.

Additional information

Funding

This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior–Brasil [Finance Code 01];Instituto Nacional de Ciência e Tecnologia em Áreas Úmidas; Brehm Funds for International Bird Conservation.