Unique hedgehog-like mammals have been filmed using their quills to communicate.
A BBC film crew captured footage of the streaked tenrecs in the eastern rainforests of Madagascar.
By rubbing together specialised quills on their backs, the tenrecs made high pitch ultrasound calls to each other in the forest undergrowth.
The footage is the first of a mammal communicating in this way, a technique called "stridulation".
The lowland streaked tenrec (Hemicentetes semispinosus) resembles both a hedgehog and a shrew with black and yellow stripes, and is found only in Madagascar.
A film crew hoping to feature these visually striking animals in the BBC series Madagascar faced a number of challenges.
As eaters of invertebrates, particularly earthworms, the best time of year to film the tenrecs was the rainy season.
The time of day also played a considerable role.
"They're active during the day and during the night but they hide a lot so it can be difficult," said local conservation expert Dr Rainer Dolch who assisted the crew in their search.
Despite being crepuscular and used to twilight conditions, the streaked tenrecs were unconcerned by the crew's lights as they foraged on the forest floor.
However, recording the sounds the animals made required more sophisticated technology.
Streaked tenrecs are known to communicate using high-pitch tongue clicks when foraging but many of the sounds are beyond human hearing.
"Most of the sounds are too high for us to hear so we took a bat detector so that we could also pick up ultrasonic noises," said researcher Emma Napper.
Using the bat detector, the filmmakers found that the seemingly "quiet" mammals were constantly communicating.
Scientists have theorised that tenrecs could also be using high pitched calls to echolocate in the dark forest, finding their way with sound rather than sight in a similar way to bats. ...
via BBC - Earth News - Bizarre mammals filmed calling using their quills.
I believe this video was taken before we knew that they were communicating with ultrasonic quill sounds. Notice how they pause at the same time? I think they are listening to the quill song when they all pause.