TOSSI – Seabird restoration at Tāwharanui

The discovery by Chris Gaskin of ōi grey-faced petrel at Tāwharanui in 2009 inspired a project to restore populations of seabirds to the pest-free sanctuary.

TOSSI, with the assistance of Auckland Council and the Seabird Trust, deployed three seabird sound systems playing a range of seabird calls. Within six months, we were seeing ōi grey-faced petrel, pakahā fluttering shearwater and kuaka diving petrel attracted to the speakers. The next step was to supplement natural breeding burrows by digging in artificial nestboxes – all designed to make the peninsula a desirable place for seabirds to breed.

Seabirds are ecosystem engineers – they bring nutrients in from the oceans to the land and greatly enrich coastal ecosystems. At Tāwharanui we recognised that seabird recovery was critical to unlocking the biological potential of the sanctuary.

Today, Tāwharanui is home to a large and growing population of ōi, a small but significant number of pakahā, along with red-billed and black-backed gulls, white-fronted tern, pied shag and little penguin. There is also the only known natural burrow of Cook’s petrel on the Auckland mainland. All up, nine species of seabirds breed in the sanctuary.

Tāwharanui has become a research site for universities studying seabird restoration and biology. It’s much easier to study birds here than getting a boat out to the islands of the Hauraki Gulf.

An important part of the Seabird Recovery Programme is monitoring seabird populations and health. “War-whoop” calls attract ōi to the ground where we can measure and tag them with a numbered metal band on their leg. We have banded over 1000 individuals, some many times over. We check nest-boxes and natural burrows for breeding success and use ground searches and special “petrel-sniffing” dogs to find new burrows. Trail cameras help identify breeding behaviour and feeding times, and spotting any pests that might threaten the growing chicks.
In the coming months, this monitoring will be crucial in assessing the impact of bird flu on seabirds within the sanctuary.