Researchers at Victoria University have uncovered surprising results about the behaviour of the little spotted kiwi.
In an acoustic study of the bird, the researchers found the kiwi, which live in pairs, call in harmony with each other using a previously unknown form of vocal co-operation.
Researcher Andrew Digby said male kiwi use their calls for long-range purposes, such as defending their territory, and female birds call for close-range purposes, like staying in contact with their partners.
It was previously thought that the difference in size between male and female kiwi was the sole reason for their calls' differences in pitch.
Dr Digby said it was also discovered the pairs synchronise their calls and have complementary frequencies, meaning they are more effective at repelling intruders.