Reproductive behaviour of a high-density population of Kiwi on Ponui Island following drought
There are five species of kiwi, all of which are endemic to New Zealand. Kiwi are flightless, nocturnal, ground-dwelling insectivores. Throughout most of New Zealand, these iconic birds are facing serious threats due to habitat loss, and predation-pressure from introduced mammals.
Ponui Island is one of several privately-owned offshore islands in the Hauraki Gulf. The main land use is farming, but significant remnants of native forest have been preserved / have persisted. In 1964, at the request of the Chamberlin family of Ponui Island, 13 North Island brown kiwi (Apteryx mantelli) were translocated to Ponui by the former Wildlife Service. These kiwi came from Little Barrier Island, Waipoua forest and Coromandel Peninsula. Since then, a thriving kiwi population has established on Ponui, which now has one of the highest-density populations of kiwi in New Zealand.
This project contributes to an extensive, longitudinal research project led by Dr. Isabel Castro from Massey University. Isabel and her team have studied various aspects of the ecology of North Island brown kiwi on Ponui Island for the past 18 years. In 2020, Ponui Island experienced a major drought and an estimated 24% of its kiwi population perished. In 2022, our team used radio telemetry to locate adult kiwi which have been fitted with transmitters, and to locate active nests; camera traps provide information on the activities of kiwi, including breeding activity. Chicks were microchipped, weighed and measured and feathers were collected for sexing the birds.
The aim of this collaborative research project is to study the effect of this drought event on the reproductive behaviour of kiwi on Ponui island. Given the pace of climate change, drought events are likely to happen more frequently; understanding the impacts on populations of kiwi, many of which experience a variety of environmental stresses, will inform and help guide future conservation and management of the species.