Massive yellow-eyed penguin decline on Stewart Is

Crashing yellow-eyed penguin numbers at Stewart Island are heartbreaking, the Yellow-eyed Penguin Trust’s science adviser says.

But Dr Trudi Webster said the massive drop in bird numbers recorded on the island after the first survey there in 12 years showed the Stewart Island birds were facing the same decline as their mainland counterparts.

Preliminary nest counts released by Ngai Tahu, the Department of Conservation and the trust yesterday showed an estimated minimum 39 nests on the island, or about 20% of 1999-2000 numbers.

The results of the first survey on Stewart Island in more than a decade showed the scale of work required to save the endemic birds from disappearing from mainland New Zealand, Dr Webster said.

On the mainland, the estimated 178 breeding pairs from Oamaru to Curio Bay — an increase of 10 pairs from last year — suggested the already dangerously low nest numbers on the mainland had stabilised for the year, but the birds continued to face huge problems, she said.

Work was still to be done to understand the pressures the birds faced at sea and some birds were being tracked while foraging.

But avian diphtheria, avian malaria and an emerging pneumonia-like form of lung congestion had affected chick survival in their nests this year.

"We do know that the birds have suffered from some major starvation events, which then make those disease events more of an issue," Dr Webster said. "It makes them more susceptible when they are not in as good of a body condition."

Poor fish availability for the birds was probably due to a mix of fishing activity, climate change and pollution.

There had been a large-scale change of the birds’ marine habitat.

This year’s comprehensive survey was just the third at Stewart Island since the turn of the century.

Preliminary results could indicate more than 200 yellow-eyed penguins, or hoiho, had disappeared from the area over the past two decades.

There were 153 nests in 2008-09 and 186 nests in 1999-2000.

North Otago had a notable 15% increase in numbers, a statement from the department said.

Te Runanga o Ngai Tahu hoiho species recovery representative Yvette Couch-Lewis said work to save the species must go on to have "any hope" of saving the birds from local extinction.

The statement said to reverse the decline, Ngai Tahu, the trust, the department, and the Ministry for Primary Industries released a recovery strategy and five-year action plan for the birds in August.

Priorities in the plan focused on managing human activities and disturbance and reducing impacts in marine and terrestrial habitats, the statement said.

In 1999-2000 on the mainland there were nearly 500 estimated nests.

After a significant drop in 1990-91, yellow-eyed penguin numbers on the mainland peaked in the late 1990s with more than 600 nests on the mainland.

Some experts have predicted the birds would be locally extinct on the mainland by 2050.