Salmonella bug killing rare birds

A young hihi.

A virtual quarantine of rare birds on Tiritiri Matangi Island in the Hauraki Gulf has left key conservation projects in limbo.

So far 10 stitchbirds, or hihi, on the island have died from a strain of salmonella that usually infects only humans and has never been found in New Zealand birds before.

"How the disease got into them is completely unknown and quite bizarre," said Department of Conservation islands biodiversity manager Richard Griffiths.

"It was completely out of the blue. The opportunity for salmonella to get into hihi is really quite limited."

He said stitchbird chick numbers this breeding season were down by around 20 per cent and while no other bird species had so far been infected, the department was taking no chances.

A hihi release in the Waitakere Ranges as part of the "Ark in the Park" project had been stopped.

Transfers from Tiri of the songbird kokako to the Hunua Ranges southeast of Auckland, whiteheads to Tauwharanui Regional Park to the north, bellbirds to Moturoa in the Bay of Islands and critically endangered takahe to Kapiti or Mana Islands near Wellington were also on hold.

"The disease was detected just weeks before the Ark in the Park transfer was to take place so it was bad timing," Mr Griffiths said.

Forest and Bird spokesman Ken Catt said the delay was disappointing.

"We'll now have to wait another year," he said.

It was likely the disease was introduced by humans to Tiri but how it was passed to the birds was a mystery. Salmonella is carried in faecal matter and causes upset stomach and diarrhoea in humans.

Meanwhile, another bumper breeding season for the migratory Cook's petrel meant dozens of crash-landings by disoriented young birds in the past week.

During April, the petrels leave their key breeding colony on Little Barrier Island to migrate as far as California and Chile.

Mr Griffiths said that for the second year running the petrels had had a bumper breeding season after eradication of kiore, or Polynesian rat, from Little Barrier in 2004. That meant more young birds crashing in backyards, as they took off at night but became disoriented by city lights.

Before the extermination, Cook's petrel chicks had an expected survival rate of around 5 per cent. This past breeding season saw that climb to 86 per cent.


Hihi (Stitchbird)

* Starling-sized nectar feeders, which vanished from the mainland around the 1880s.
* They were once common throughout the North Island.