'Eavesdropping' technology used to protect one of New Zealand's rarest birds

February 5, 2019, Zoological Society of London

Remote recording devices used to 'eavesdrop' on a reintroduced population of one of New Zealand's rarest birds have been heralded as a breakthrough for conservation.

Scientists from international conservation charity ZSL (Zoological Society of London), Imperial College London and conservationists from the Rotokare Scenic Reserve Trust used acoustic monitoring devices to listen in on the 'conversations' of New Zealand's endemic hihi bird, allowing them to assess the success of the reintroduction without impacting the group.

For the first time ZSL scientists were able to use the calls of a species as a proxy for their movement. A happy hihi call sounds like two marbles clanging together in what is known as the 'stitch' call. Scientists saw the calls change from an initial random distribution to a more settled home range—marking the hihi reintroduction and the new method a success.

The study, published in Methods in Ecology and Evolution today (5 February 2019) was carried out in the Rotokare Scenic Reserve in the Taranaki region of North Island, where 40 juvenile birds were released in April 2017. The first time hihi have been seen in the region since their regional extinction over 130 years ago.

Once found across northern New Zealand, the hihi or stichbird (Notiomystis cincta) are now classed as locally extinct across most of their former range, due to habitat loss and fragmentation and the spread of non-native invasive mammal predators. There are only a few thousand adults left in highly protected reserves.

Dr. John Ewen, Senior Research Fellow at ZSL's Institute of Zoology said: "Hihi are an important native species, who play a crucial role in pollinating indigenous plant species and need a pristine environment in which to thrive. Reintroduction, or translocation, is considered the most effective conservation action we can take to save the hihi bird in New Zealand, but as with other reintroduction programmes for other species around the world, we've found it can be challenging to accurately monitor their success.

"Physically monitoring animals in the field or fitting them with radio-trackers can be invasive, expensive and more importantly can influence the behaviour or survival of released individuals, which could drastically influence our understanding and outcome of the reintroduction.

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