Environment – Meet the Ōi on Tiritiri

Most visitors’ first experience of Tiritiri Matangi is limited by the ferry schedule to daytime hours, but for those staying overnight a new perspective appears as they can rise before daylight and hear the amazing dawn chorus. And, if they have enough energy, it’s worth taking a nighttime walk to search for penguins, kiwi and tuatara. As a seabird enthusiast, I’m always keen to head out at dusk to listen for the arrival of nocturnal burrow-nesting seabirds. On a good night, the sky is full of hundreds of calling birds circling the island and during the nesting season, some will come to land.

While we were on the island for the May translocations of hihi/stitchbird and tīeke/saddleback to Shakespear Regional Park, the team took the opportunity to search for ōi/grey-faced petrels. You can see images and find out more about ōi on the NZbirdsonline website (check out their strange ‘squeaky gate’ calls). Most of our burrow-nesters are strongly site-faithful, returning to the location of their hatching to find a partner and raise their young. But young ōi are more inclined to wander around visiting other colonies before deciding where to settle. Over many decades on Tiritiri, ōi have been banded with numbered metal leg rings, but in recent years only a few dozen have been caught and banded. Over four amazing nights, we caught 149 individuals, 18 of which were already banded. Ten of these had been banded on Tiritiri including one from seven years earlier. There were also two from Motuora, three from Shakespear and one from the Noises. In previous years we’ve had birds from Tawharanui and Te Henga on the west coast.

Catching ōi is a challenging task. The first part is easy but very strange. All that’s needed is for the catchers to call out with a high-pitched yodel. Birds on the ground respond to this and walk towards the yodeller who can then pick them up. I wonder who discovered this and what they thought they were doing at the time? They are quite large birds with sharp claws and a very strong sharp bill, so any unwary team members received a few scratches for their efforts. Ōi are long-lived, some surviving 40 years, so we will have many opportunities over the next few decades to follow the fortunes of these banded birds.

If you’d like to visit the island, the Explore ferry group is offering large fare discounts for members of the Supporters of Tiritiri Matangi, and there’s a ‘kids go free’ offer, both until the end of July. Also, there’s a special dawn chorus trip planned for Saturday October 4 with the ferry departing Auckland at 4am and Gulf Harbour at 4.55am.