article_snippet.sent: While these calls have been known about since the 1940s, these calls have not been studied in detail due to these calls low volume and because these calls are almost indistinguishable to the human ear.
article_snippet.sent: The researchers calls and behaviour.
article_snippet.sent: The researchers were the least audible of the calls.
article_snippet.sent: The ability to produce calls that are context-specific is necessary for communication to direct the attention of others.
article_snippet.sent: The researchers believe this may help keeps tabs on an individual's whereabouts.