By Alyce Collins
These Siamang apes have an unusual vocal call that sees their throats bulge out.
Recorded by Diana Feeney in March 2013, the Siamang apes were in their enclosure at Taronga Western Plains Zoo in Dubbo, NSW flexing their vocal chords.
The two adults yell out their territorial call, as they do their throat pushes out like a balloon.
Diana said: “I was amazed at the performance and that I was able to capture it on video.
“I was surprised to see their throats balloon out and hear the noises they were making.”