It's a very different kind of conservation project – a native New Zealand bird is threatening another native species and an ice cream brand named after the island it is happening on is intervening.
That's the strange, but true, synopsis of a three-year project launched late last year on Kāpiti Island, off the coast of Wellington. It involves the Department of Conservation, the Wild Ark conservation movement, local iwi and Kāpiti ice cream, the brand which borrows the name and whose logo contains the island's distinctive silhouette.
The bird needing help is the tītī – also known as the sooty shearwater or muttonbird. It is not a nationally threatened species though it is very much being threatened by another New Zealand native species itself classified as "vulnerable" – the weka.
Weka are omnivores and prey on, among other things, tītī chicks. They are clever hunters, entering the burrows when the parents are away causing the tītī population to decline alarmingly over the last 20 years. Most former Kāpiti Island colonies mapped in the past are now gone.
Wild Ark's General Manager (Asia, Africa, Pacific), Kirstin Scholtz, says the project is unusual in that it is not dealing with an endangered species – though she quickly points out that the tītī is certainly threatened with extinction on Kāpiti.
"We know too that it is a very important part of the local iwi's culture and heritage and, in our work, we believe it is important to protect cultural heritage and everything associated with that."
When Kāpiti ice cream contacted Wild Ark, they quickly partnered up to support DOC's research, aimed at finding a sustainable management solution for boosting the burrowing seabirds' numbers.
"We know tītī aren't on the nationally endangered list, but on Kāpiti they are a taonga to local iwi, and a critical part of restoring the island's ecosystem," says Mel McKenzie, Head of Marketing at Tip Top. "However, their colony is near the point of collapse and unfortunately weka, another island taonga, are assumed to have caused this dramatic decline.
McKenzie says when the company heard of the potential effect on the island, it knew it was the right project to direct some of its conservation efforts towards: "The Kāpiti Coast is the origin of Kāpiti ice cream, so we wanted to give something meaningful back to the local community.
"Saving the tītī on Kāpiti Island felt like the right thing to do to further the conservation efforts in this treasured part of New Zealand."
The tītī's beneficial effect on Kāpiti comes from their daily foraging trips out to sea. When they return, they bring back essential nutrients in their droppings which greatly benefits Kāpiti's vegetation.
Graeme Taylor, DOC's Principal Science Advisor, Marine Species, says it's essential to get to the bottom of the decline of the tītī population on Kāpiti.
"We have neighbouring Mana Island, where the tītī population is steadily increasing following the removal of mice and farm stock by the early 1990s." he says, "It [Mana] is without weka and provides a local comparison.
"This project will identify ways to reduce predation by weka and experiment with novel exclusion methods, supported by robust monitoring of nesting success over several seasons. At the same time, it explores the indigenous knowledge about each of these species, their history on Kāpiti and how that Mātauranga Māori can guide long term management."
"We need to address the drivers of this decline, and this is how we find out how. The Mana and Kāpiti comparison will help to tease out the land-based threats, such as nest flooding and weka predation, from changes in the marine environment due to climate change."
Scholtz says possible remedies are some sort of man-made burrow access barriers that can stop the weka from entering or ways to reduce the numbers of weka around the colony during the vulnerable nesting phase.
"That's part of what is so interesting about this project – it isn't caused by humans or habitat loss for once and it is purely over concerns for an important bird being predated upon by another bird of equal importance to the island."
The project is based on the two hulls/e rua nga takere approach to science and provides support for two students/tauira mahi to undertake the study/matai with support from DOC and their tertiary institutions.
Seabird scientists and DOC staff have conducted initial surveys on Kāpiti and Mana to compare breeding results. Over the most recent breeding season, results were grim - no chicks from the Kāpiti study survived, assumed to be mostly due to weka predation.
However, only 22 per cent survived on Mana due to extreme weather causing burrows to flood, proving these birds are facing multiple pressures.
Tītī chicks hatch in January and spend several months fattening up before fledging from burrows in April. They can fly as far as Alaska over our winter months before returning to their colony to begin pairing up in 3-6 years.