World’s largest forest birds may produce world’s deepest bird calls

Cassowaries’ low-frequency sounds may give insight into dinosaur communications

A family of huge forest birds living in the dense jungles of Papua New Guinea emit low-frequency calls deeper than virtually all other bird species, possibly to communicate through thick forest foliage, according to a study published by the New York-based Wildlife Conservation Society.

Published in the recent issue of the scientific journal The Auk, the study says that three species of cassowaries – flightless birds that can weigh as much as 125 pounds – produce a “booming” call so low that humans may not be able to detect much of the sound. The researchers draw similarities between the birds’ calls and the rumbling elephants make to communicate.

“When close to the bird, these calls can be heard or felt as an unsettling sensation, similar to how observers describe elephant vocalizations,” said WCS researcher Dr. Andrew Mack, the lead author of the study.

Known not only for their great size, but also their spectacular, helmet-like bony casques, and blue and red skin around their neck and head, Cassowaries are highly vulnerable to over-hunting and habitat loss. They are also considered among the world’s most dangerous birds, due to their ability to kick when threatened, using a dagger-like spur on their feet with sometimes deadly results.

The authors and their collaborators are now pursuing studies that examine the physics of low frequency sound production and reception. They speculate that the cassowaries’ casque might serve a function in both, most likely sound reception.

“These investigations are exciting because many dinosaur fossils exhibit casques at least superficially similar to those of living cassowaries,” said Mack. “No one knows for sure what purpose these served in these dinosaurs, so further study of living cassowaries might provide clues to how dinosaurs communicated.”

Coincidentally, the great early 20th Century dinosaur hunter, Barnum Brown, described the Corythosaurus, otherwise known as the Corinthian Helmet Lizard as “cassowary-like.