Conservation by numbers

New Zealand has amazing birdlife: nocturnal parrots, birds that can't fly, unique and beguiling birdsong, and varieties that turn up after 50 years of being thought extinct.

Stephen Marsland, wearing a blue hoodie, leans against a tree with green vegetation behind him.

Unfortunately, many native species require wildlife management programmes and their clever camouflage often makes them hard to monitor.

Which is why Professor Stephen Marsland from the School of Mathematics and Statistics is co-leading a large, inter-disciplinary project using mathematics, data science and new technology to help New Zealand birds survive.

The project involves collaboration with mathematicians, ecologists, statisticians, electronic specialists, engineers and iwi from across New Zealand.

“The aim of this project is to take recordings of birds collected in the field and identify all those that are calling, using mathematical and computational methods such as machine learning,” says Stephen.

“Our research is unique as it uses automatic field recordings and the birds can range from five to 500 metres away from the microphone. This means that there can be a lot of background noise, which can make it hard to distinguish the calls.

“Sometimes there are a lot of species singing all at once. If you have a small number of species and high-quality recordings then the problem is reasonably simple, but this isn’t necessarily realistic. We’re interested in the real-world version where you have a lot of species and noisy recordings.”

Stephen and his team of researchers use their knowledge of the different species and statistical methods to turn the call rates into estimates of the numbers of birds present. “The software that we are writing will be freely available to everybody who wants to use it, from community groups through to the Department of Conservation and other researchers,” he says.

“Not only are we developing new mathematical techniques, but we also get to try them out in the field and see the difference they make.”