Researchers studying the New Zealand storm petrel have, for the first time since they were rediscovered nine years ago, found an egg of the critically endangered birds.

The petrels were presumed extinct then rediscovered in 2003, more than a century after the last sighting.

In February last year the birds were successfully tracked to breeding sites on Little Barrier Island (Te Hauturu-o-Toi) in the Hauraki Gulf, but only recently has an egg been discovered.

NZ storm petrel project scientists took the opportunity when the female was off the nest to check the egg was fertile and record data, Department of Conservation principal science advisor Graeme Taylor said.


"It was exciting to see the egg of a bird once thought to be extinct."

Measuring a mere 31mm by 23mm, the egg was white with a fine dusting of pink spots concentrated at one end, he said.

"The fact it has taken until 2014 for scientists to observe one of these tiny eggs reflects how much we still don't know about New Zealand's natural environment and particularly for marine species."

New Zealand storm petrels

• The seabirds are sparrow-sized

• They spend most of their lives at sea, coming ashore only to breed

• They breed in burrows, are nocturnal when flying to and from their nest sites

• They lay only one egg, which they incubate for more than a month.