Researchers from Curtin University in Australia have recorded vocalisations of wild short-beaked echidnas during the breeding season, proving that these spiky creatures can vocalise. Echidnas are egg-laying mammals in Australia, known for their unique features and behaviours. The recorded sounds included cooing, grunting, wheezing, and exhalation, challenging the previous belief that auditory communication was absent in echidnas, with only recognised "sniffing" noises.
The study captured adult echidnas making these sounds alone or in the company of other echidnas, and all vocalisations were recorded during the breeding season, suggesting a connection to reproductive activities. The researchers used handheld microphones and an unattended camera with a microphone at the cave entrance frequented by echidnas for the recordings.
The findings resolve the debate about when early mammals started making sounds for communication. Monotremes, like echidnas, are egg-laying mammals, and the discovery of vocalisations in both echidnas and platypuses, another monotreme, suggests that the common ancestor of monotremes and other mammals could also vocalise.
Acoustic communication is standard in many terrestrial vertebrates, including mammals, birds, reptiles, and amphibians. The sounds produced play various roles, such as attracting mates, defending territory, exchanging information, and communicating with other animals.
The study also hints at the development of acoustic communication in mammals, indicating that it likely evolved 100 to 200 million years ago, predating the divergence of monotremes from other mammals. While other forms of communication, such as vibrational and chemical signals, may have appeared earlier, the study reinforces that acoustic communication through sound has ancient roots in the mammalian lineage.
The researchers acknowledge the mystery surrounding the purpose and meaning of echidnas' vocalisations but note that the sounds were only heard from adult animals during the breeding season, suggesting a link to reproductive activity. This discovery adds to our understanding of the behaviour of these unique Australian creatures and highlights the ongoing mysteries surrounding their communication.