Gemma's fieldwork in Rarotonga's mountains leads to a breakthrough for seabird conservation in the Cook Islands
In this first-hand account, VSA volunteer Gemma Langley shares her experience working on Te Manu Tai o Te Kūki ‘Āirani – a new seabird monitoring project launched to better understand which petrel and shearwater species are breeding in the Cook Islands. Working alongside local landowners, conservation groups, and seabird experts, she joined field surveys in Rarotonga’s mountain peaks, deploying monitoring equipment, searching for nesting sites, and recording predator activity. Gemma’s work has contributed to a major conservation milestone: the first active Tahiti Petrel burrow on the island. Here, she shares what it’s like to be part of this important conservation effort and the discoveries made along the way.
Gemma's story
As part of my volunteer placement, I’ve been actively involved in Te Manu Tai o te Kūki ‘Āirani; a seabird monitoring project launched in March to determine which species of petrels and shearwaters are currently breeding in the Cook Islands. This collaborative effort brings together local landowners, Muri Environment Care, the Cook Islands National Environment Service, Te Ipukarea Society, and seabird expert Dr André Raine from Archipelago Research and Conservation (ARC) in Hawai’i. This project is supported by the National Fish and Wildlife Foundation, with additional backing from the Secretariat of the Pacific Regional Environment Programme (SPREP), Island Conservation, BirdLife International Pacific, and the Northern New Zealand Seabird Trust.
Petrels and shearwaters belong to a group of ocean-going birds known as the tubenoses. Because they spend most of their lives far out at sea and only return to nest in remote, high-elevation mountain sites, they are rarely seen and remain poorly understood in the Cook Islands. However, they play a vital ecological role. These seabirds feed on marine life and return to land to nest, depositing guano – fish-rich, nutrient-dense waste – directly into the mountain ecosystems. This guano fertilises native vegetation and helps transport marine nutrients from ridge to reef.
The project involves hikes up Rarotonga’s major peaks, including Ikurangi, Te Manga, Raemaru, Mangatea, Maungaroa, Te Ko’u, Maungatea, Koputu and Te Rua Manga. Song meters – audio recording devices programmed to ‘listen’ for seabird calls day and night – are serviced on each maunga to improve understanding of which seabird species are present and when they are active.
When we are in the field we also search for physical signs of nesting activity, such as burrows and seabird-created trails, and deploy motion-activated camera traps to confirm breeding behaviour and monitor for introduced predators like cats, rats, and dogs.
In just the early stages, the project has also revealed exciting discoveries about Rarotonga's little-known seabird populations. By day, Herald Petrels were observed soaring over several of the island's peaks. At night, surveys recorded high levels of Tropical Shearwater activity. The most significant finding came in the upper Takuvaine Valley, where the team heard the eerie, dinosaur-like calls of a Tahiti Petrel and shortly after located a promising burrow site — the first recorded evidence of Tahiti Petrel activity on Rarotonga.
A motion sensor camera installed at the site later confirmed the first ever active Tahiti Petrel burrow recorded in Rarotonga. Footage showed two petrels using the burrow – strong evidence of a breeding pair. This is a major milestone for Cook Islands conservation, as the Tahiti Petrel is classified as Near Threatened by the IUCN. I’ve since been studying burrow camera footage to gain insight into the pair’s behaviour to understand the breeding season for Tahiti Petrels on Rarotonga.
However, camera footage also revealed a significant threat: the camera captured footage of rats visiting the burrow site. As ground-nesting birds, petrels are highly vulnerable to introduced predators. In response, we have started a predator control programme in the upper Takuvaine Valley which involves placing bait to reduce rat numbers and help protect this important breeding site.
This project has given me the opportunity to engage in meaningful, hands-on conservation work that supports both local biodiversity and broader ecosystem health. It’s been an incredible experience working alongside others in Rarotonga’s mountains, helping to uncover important new information about understudied seabird species in the Cook Islands. Along the way, I’ve also had the chance to explore some of the island’s most beautiful and remote places – areas few others ever get to visit. I’m excited to keep building on this work in the months to come.
