AsianScientist (May 3, 2013) – A group of researchers in New Zealand have discovered that kiwis produce calls in harmony with each other by using a previously unknown form of vocal cooperation.
The researchers at Victoria University of Wellington studied the calls of the little spotted kiwi, New Zealand’s second rarest kiwi, over a period of three years. During this time, they measured hundreds of calls made by a population of the birds living at the Zealandia sanctuary in Wellington, New Zealand.
From studying their calls, the researchers made the surprising discovery that kiwis, which live in pairs and are thought to mate for life, sing in harmony with their mates by synchronizing their calls and having complementary call frequencies.
By calling together in harmony, a pair of male and female kiwis become more effective at repelling intruders than if they were to call alone. This is the first time such cooperation in frequency and time has been reported in bird “duets”.
The researchers also found that, contrary to what they previously believed, size differences between male and female kiwi are not the sole cause of the differences in the frequency, or pitch, of the calls the birds make.
“Instead, male and female kiwi appear to call for different reasons, with male kiwi using their calls for long-range purposes, such as defending their territory from other kiwi, and female birds using calls for close-range purposes, like staying in contact with their partners,” says Dr Andrew Digby, the lead author of the study published in Ibis, the world’s leading ornithological journal.
“Calls are an important part of kiwi conservation since they provide an inexpensive, efficient and non-invasive way to monitor these mysterious birds.”
“But, we actually understand very little about why kiwi call, and the calls of most kiwi species have never been studied, so this research is important for helping us gain a better understanding of one of our national icons.”
The article can be found at: Digby et al. (2013) Vocal Cooperation Between The Sexes In Little Spotted Kiwi Apteryx Owenii.
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Source: Victoria University of Wellington. Photo: RobiNZ (Robin Capper)/Flickr/CC.
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