New lecturer comes full circle

14 February 2017

Close up image of Dr Ben Stevenson inspecting a snapper.
Dr Stevenson inspects a snapper, one of the species he has explored in his research.

Dr Ben Stevenson is an expert on statistical methods for estimating animal populations. If you want to know how to estimate frog density from their chirps, for example, he’ll tell you how it can be done.

And he’s just increased the headcount at the Department of Statistics by one after returning from doctoral study at Scotland’s University of St Andrews. Dr Stevenson completed his BSc(Hons) and MSc degrees in the Department of Statistics; his masters analysed fishing success against the lunar calendar, and he became interested in statistical methods that allow ecologists to make inferences about animal populations. “Ecologists are often interested in things like how many animals live in a particular area, or how they move about and use their habitat”, he explains. “However, these can be difficult to infer from wildlife survey data.” 

His PhD explored a class of model known as spatial capture-recapture, which can estimate animal density, among other things, from records of where and when identifiable individuals are detected. A “good chunk” of his PhD was on acoustic spatial capture-recapture, with one application the estimation of frog density from recordings of their calls, collected by a microphone array. Following on from that, Dr Stevenson is now developing spatial capture-recapture methods for surveys that use cameras. One potential application is to a camera-trap survey of leopards in Kruger Park, South Africa.

“Cameras are triggered by movement, and individual leopards are identifiable by their unique spot patterns,” he explains. But many groups of animals look rather alike, and Dr Stevenson is working on ways to estimate the things scientists are interested in when they can't recognise individuals.

Dr Stevenson says he didn’t need to think twice when he was offered a job back home; working alongside the department’s Associate Professor Rachel Fewster, an expert in statistics relating to conservation, ecology, and animal behaviour, was too good to miss.

“Despite never having worked directly with Rachel prior to leaving for the UK, I then collaborated closely with her during my PhD,” he says. “She’s an excellent researcher and we work well together. It’s a real bonus to be coming into a department with a ready-made collaborator, and this also influenced my decision to return to Auckland.”

Dr Stevenson says that studying towards his PhD overseas was “hugely beneficial” and he recommends it to aspiring academics. “Going elsewhere provides an opportunity to immerse yourself in a totally new academic environment and forge new collaborative relationships. And studying in Europe also helps travel funding go that much further – I went to Iceland, France, South Africa, Ghana, Canada, and the USA over the course of my studies for conferences, research visits, and to teach workshops.”