Marsden win for Rachel Fewster

15 November 2017

Associate Professor Rachel Fewster
Associate Professor Rachel Fewster

Associate Professor Rachel Fewster has landed a $680,000 Marsden Grant that promises to supercharge our biodiversity monitoring toolkit.

“In a nutshell, this project is about getting higher-value information from routinely collected data,” Rachel says. “Instead of wanting more data or different data, we want more ingenious use of the data already collected. We’re aiming to develop new tools for assessing how our native species are faring, and whether their populations are trending upwards or downwards.”

The researchers are taking a two-pronged approach. Firstly, Rachel’s Victoria University collaborator, Professor Stephen Marsland, and his team will develop ways to automatically identify the recorded calls of kiwi and other birds. They will be able to leave recorders playing for long periods without human screening, generating larger sample sizes than before.

The second part is where statistics comes in – converting this information into abundance estimates. There are various ways of monitoring wildlife population size, but for elusive forest-dwellers like kiwi, the most promising way is to use acoustic monitoring with microphones. But there is not yet a statistically robust method for converting call counts into abundance estimates.

Rachel’s new idea is to compare the times of syllables received at one microphone with the times at which they are received at another, a known distance away. By comparing the within-mic intensity of syllables with the between-mic intensity, she will be able to estimate how detection diminishes over distance without needing to measure the distances between birds and microphones. “Once we know how the pattern of detection decays over distance,” Rachel explains, “we can start to estimate the number of birds that were never detected, and therefore the population size.”

Rachel greeted news of her win with relief and gratitude. “Applying for these grants is a huge outlay of time and energy – several weeks’ work in my case,” she says. “I am genuinely excited about this project, because we have an opportunity to make a real difference in conservation by following it through.” But Rachel adds that she knows what it feels like to miss out at the final hurdle, “and I feel for the people who missed out this time. I'm grateful to have the opportunity to move our ideas forward.”

  • Stephen and Rachel will integrate their new methods into the freely available AviaNZ software program, publicly available software to analyse acoustic data for conservation efforts.