Student profiles

Learn about the research and experiences of current students in the School of Biological Sciences.

Andrew Digby

Andrew Digby with little spotted kiwi

Andrew Digby is a biology PhD student using new acoustic technologies to study the little spotted kiwi in Zealandia. He already has a PhD in Astronomy and completed a Post-Doctoral Fellowship with NASA, but became captivated with conservation when he came to New Zealand in 2006.

"I was doing volunteer work at Zealandia, including kiwi call counts. I started thinking that there might be some better ways of doing the counts, using some of the techniques I'd learned elsewhere. I think it's exciting to apply technology from one area of science to another, and my physical science experience has certainly allowed me to look at some new ways of doing things with wildlife monitoring, he said.

Kiwi calls can be used to monitor population numbers and  the status of territories and different pairs of birds. Andrew is also trying to determine if each bird has a signature call which can be used to identify it, and studying birds in different locations to see if unique 'dialects' are developing there.

Little spotted kiwi, his main study group at Zealandia, are the second rarest kiwi species in New Zealand and all birds are in protected environments, as their chicks would not survive predation in the wild. (Rowi, formerly known as Okarito brown kiwi are the rarest.) Adult birds are vulnerable to dogs and ferrets and the chicks to stoats as well - the birds have a distinctive smell that makes them attractive to dogs and a weak ribcage that can be broken with a single dog bite.

All living little spotted kiwi are descended from seven birds at most, from a population on Kapiti Island. "If someone hadn't thought to put five birds on Kapiti Island 100 years ago, we wouldn't have any at all now.

Andrew is keen to find out what the reasons for kiwi calls are. "It's assumed that important functions are to defend a territory and to contact a mate, but I suspect there may be more to it than that. Sound is obviously a really important means of communication for kiwi – it's dark and there are not many of them in one area – but we may be missing a whole lot of information because we're not looking closely enough.

Spectrograms of calls are like printed music scores and allow calls to be recorded and analysed visually and digitally. "I'm training call recognition software to look for kiwi and at the moment it is behaving like a pretty deaf person, but as I tweak it, it will get more sensitive.

Little spotted kiwi spectrogram
Spectrogram of a male little spotted kiwi call. Listen to the kiwi call (4 MB).

"Using this new technology means we have a more reliable, permanent record of calls over a much longer timescale than is possible with even the most willing volunteers. The recorders are left out for weeks at a time and set to turn on for night time. We have also set them out in a grid so that we can get some spatial information too – effectively mapping their movements with sound.

"I've always wanted to work in conservation, but I never thought it could be a career. The more I talked to people, the more I realised I needed to do a PhD first, so I set about it, thanks to the support of my very understanding partner. I'm also grateful to Victoria for taking me on and for the Victoria Doctoral Assistantship I was awarded. DoC (the Department of Conservation) has been amazing too – I've learned so much from them, including practical things like how to band and weigh birds."