In a major first for Tāwharanui, a pair of Cook’s petrels successfully raised a chick at the open sanctuary during the 2020-21 summer.

It is thought that this success is the first on the mainland of Aotearoa in a long time, maybe more than 150 years.

In 2019, the mainland burrow was discovered by Auckland Council ranger Amy Waldmann and German intern Juliane Mommert while checking for stoats.

They found an egg abandoned outside the burrow and subsequent investigation by seabird scientist Edin Whitehead and Tāwharanui Open Sanctuary Society Inc. (TOSSI) volunteer James Ross revealed a dead Cook’s petrel inside.

Trail camera pictures showed a pair of Cook’s petrels had adopted the burrow and hopes were high for the 2020-21 season. The camera and a dog trained to find petrels confirmed the burrow was in use and was being visited in a routine that strongly suggested an egg had been laid. However, getting the final proof was tricky.

Cook’s petrels are small grey-and-white petrels. Their goat-like calls (kek-kek-kek) are often heard at night north of Auckland as they return from feeding in the Tasman Sea to their burrows on Hauturu (Little Barrier Island).

Cook’s petrels formerly bred throughout both the North and South Islands, on mountain tops and ranges. After hundreds of years of predation by introduced mammals, they became confined to just three islands. In the north the largest colony, more than a million birds, is on Hauturu and there are a small number on Aotea/Great Barrier Island. Control of cats and kiore on Hauturu has led to a significant increase in seabird numbers in the past 15 years.

In southern New Zealand, several thousand Cook’s petrels breed on Codfish Island.

The chick that successfully fledged at Tāwharanui is the first known Cook’s petrel chick on the mainland of New Zealand for more than a century.

After a week of exercising its wings, the chick left its burrow for the last time on 9 March. It will now fly across the Pacific to feed off the coast of California before returning to New Zealand in September.

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