COVID-19 lockdown restrictions mean that much conservation work around New Zealand is on hold. But in a remote part of Fiordland, restoration efforts are continuing every night, regardless of access constraints, social distancing, and weather conditions. Te Papa vertebrates curator Colin Miskelly describes the pioneering efforts being made to attract seabirds back to Coal Island/Te Puka Hereka in Preservation Inlet.
Coal Island must be the most remote community-led island restoration project in the country. Located in Fiordland’s southernmost fiord, Preservation Inlet/Rakituma, Coal Island is more than 100 km south-west of Te Anau, and more than 90 km from the nearest helicopter hanger. Just getting there is a logistical challenge.
Restoring the birds
In February 2020, I was privileged to join members of South West New Zealand Endangered Species Charitable Trust on a mission to restore seabirds to the 1163 ha island, which lies alongside Puysegur Point. The Trust was formed in 2004, and worked with the Department of Conservation (DOC) during 2006 to 2008 to eradicate stoats, deer and mice from the island. Since then, DOC and the Trust have successfully translocated three rare native bird species to the island, with Haast tokoeka (kiwi) released in 2010, and South Island robins/kakaruai and yellowheads/mohua in 2015.
These restoration projects all involved catching birds at other sites (up to 300 km away) and transporting them to release sites on the island. In contrast, the method chosen for seabird restoration was passive rather than active, but still required a lot of sweat and hard work.
A survey of seabirds on other islands in Preservation Inlet by a joint Department of Conservation and Te Papa team in 2017 located two colonies of mottled petrels (about 1000 burrows estimated) and at least eight colonies of sooty shearwaters (at least 8,400 burrows estimated). Both species feed far out to sea – even as far as Antarctic pack-ice – and need to fly past Coal Island in order to return to their colonies. Neither species has been seen on Coal Island, but we saw both species flying over our campsite at night.
Our cunning plan was to give the impression that Coal Island has active colonies of both species, in the hope that birds flying past would be attracted to land and seek a burrow and a mate. The technique is known as ‘acoustic attraction’, and involves broadcasting calls of birds recorded at breeding colonies.
A sample of the mottled petrel calls now playing on Coal Island (original sound files supplied by Rachael Sagar and Denise Fastier, Department of Conservation)
Both species return to their colonies under the cover of darkness, and so the solar-powered sound systems are programmed to broadcast their calls only at night. And that means every night for as long as the car battery lasts and the sun shines enough to keep it charged. As no further human input is required, the sound systems should continue working regardless of how long COVID-19 lockdown restrictions are in place.
A sample of the sooty shearwater calls now playing on Coal Island (original sound files supplied by Graeme Taylor, Department of Conservation)
Building for a brighter future
The South West New Zealand Endangered Species Charitable Trust (through the Mohua Charitable Trust) had successfully raised funds for three sound systems. Our first challenge was selecting three widely-spaced sites that were well-positioned for birds flying past, that had suitable habitat for the birds to nest, and that had a north-facing site nearby for installation of the solar panels.
We were able to get most of the equipment delivered by helicopter to each site, but there were still heavy loads of tools to carry between the sites, and it took up to 3 hours to move between the two most widely separated sites. Once at the sites, it took several hours to assemble the sound systems and dig sufficient starter burrows to ensure that any birds that landed could find a site out of the weather and away from flying predators (New Zealand falcons/kārearea are resident on the island).
Attracting shearwaters and petrels to new breeding sites can take time, but it is a proven technique. Solar-powered acoustic attraction systems have been installed at several seabird restoration sites elsewhere in New Zealand. Many of these are at sites where chicks have been translocated and hand-fed, but at a few sites (including Raoul Island in the Kermadec Islands, and Young Nick’s Head near Gisborne), acoustic attraction alone has enticed other petrel species to land and breed.
We look forward to progress reports from Coal Island over the next few years.
With thanks to the South West New Zealand Endangered Species Charitable Trust for organising the trip, ANZ Staff Foundation, Mohua Charitable Trust, and DOC Community Fund for funding contributions (including sponsoring purchase of the acoustic attraction equipment), and Fiordland Helicopters for donating flying time. And of course my fellow team members Megan, Hannah, Fi, Jacinda and Fred for their good company and getting it all done in the limited time available.