Fishermen asked to keep eye out for new-look black petrels

By ANNE BESTON, Environment Reporter


Boaties on the Hauraki Gulf this summer are being asked to report sightings of a big black or black-brown seabird with gaudy paint on its back to the Department of Conservation.

Two researchers are marking the backs of about 20 threatened black petrels with fluorescent paint to find out more about the birds, which breed in New Zealand only on Great Barrier and Little Barrier Islands.

"It's a pretty basic population study, but in saying that we still don't know how many are out there," said researcher Joanna Sim, who is carrying out the work for the Department of Conservation in partnership with scientist Elizabeth Bell of Wildlife Management International.

Black petrels have a prominent hooked bill similar to other members of the "tube-nosed" seabird family, such as albatross and shearwaters.

They migrate between New Zealand and the eastern tropical Pacific Ocean from west of the Galapagos Islands to southern Mexico, returning to New Zealand between October and December each year to raise chicks.

They are slightly smaller than a black-backed gull, are black or browny-black all over with black legs and feet and glide on stiffly-held wings with only a few wing beats before diving into the sea for their favourite food, squid.

But their feeding habits bring them into conflict with longline fishermen because they go after the squid used as bait.

Although the birds have been tagged since the 1970s, the painted birds will be given different colours depending on whether they are adult breeding birds or young single birds.

Ms Sim said the spray-painting, which would not harm the birds, was a bit primitive but was the best way to gain information about numbers and behaviour.

The project came about when dummy radio transmitters were trialled on the birds two summers ago and boaties reported seeing them.

"That was actually valuable information, so we thought we would do this basic colouring project and people could report seeing them," Ms Sim said.

"The more information we have the better."

There are thought to be about 1700 breeding pairs of black petrels and about 4000 adults in total.

Before European settlement, which brought with it a number of predators including cats and mustelids such as stoats and weasels, they were found throughout the North Island and the north-western South Island.

Great Barrier is mustelid-free, but cats are still a threat to the birds, which breed in burrows in dense bush.