Hunua Ranges' birds fighting back

By ANNE BESTON environment reporter

In the dark, bush-clad hills of the Hunua Ranges, the only sounds that disturb the silence are the cry of a kingfisher and the slap of flax leaves whipped by the wind.

The South Auckland ranges cover 15,000ha, about the same size as the Waitakeres in the west, and sit almost at the edge of the Firth of Thames.

They run from near Clevedon in the north to below Kaiaua in the south and are surrounded by a clutch of other regional parks on their eastern border - Omana, Umupuia, Tapapakanga and Waharau.

Early settlers failed to tame the brooding, inhospitable hills and the foundations of abandoned cottages can still be found among the undergrowth.

The settlers also left a living legacy, one that would change the landscape of this forest. Stoats, possums, rats and goats devastated entire bird populations - the stitchbird, North Island robin, saddleback and kakapo have all gone.

But in the early 1990s, conservationists discovered a tiny population of kokako, still struggling against the odds in one of the most inaccessible parts of the forest.

The Auckland Regional Council, in partnership with the Department of Conservation, mounted a rearguard action to save them and to restore the forest to its former glory.

After more than six years, the council finally has some results to boast about. Since 1994, $1.3 million has been spent on controlling possums alone, with an estimated reduction in numbers of more than 80 per cent.

About $100,000 a year is spent on killing goats, including the use of "Judas" goats to locate hard-to-find herds. A lone goat is captured, fitted with a radio collar and tracked by hunters as it rejoins the herd.

The goats are then killed and the Judas goat is left to find another herd.

Goats eat about 70 per cent of plants that the kokako eats.

A survey at the beginning of this year found that native plants, including cabbage tree, fuchsia, mahoe and kohuhu, have all regenerated since the goat programme began in 1995.

During the kokako breeding season, 800 traps surround the 19 birds that live within the intensively managed 600ha protection area.

From one breeding pair six years ago, the population is now 19.

It is hoped the five known breeding pairs among them will have a bumper season after high numbers of rats killed the only offspring last season.

Stoats are another big threat to the kokako, and twenty have been killed since winter.

Regional council heritage scientist Dr Tim Lovegrove is upbeat about the future of the Hunuas as a unique wilderness area within easy reach of Auckland.

"I think we're just on the upward climb of a curve that could see a spectacular increase in kokako numbers.

"I reckon that in a few years, you will be able to walk around the Hunua Falls and see kokako."

Another species making a tentative bid to return to the ranges is the bellbird. They have been spotted at Waharau on the eastern side of the Hunuas but, unlike kokako, they will be left to their own devices.

"There are some populations you can molly-coddle but some survive no matter what is chucked at them," said Dr Lovegrove. "Bellbirds are one, and there's a natural recolonisation of the ranges going on."

As well as being the only home to kokako within Greater Auckland, the Hunua Ranges supply more than 60 per cent of the region's water.

The three reservoirs - Wairoa, Mangatawhiri and Mangatangi - are surrounded by some of the only original forest left around Auckland.

But the Hunuas have always been something of a poor cousin to the more high-profile Waitakere Ranges.

They have roughly half the visitor numbers of the Waitakeres.

But the regional council is upgrading walkways and wants Aucklanders to take more advantage of the Hunuas, despite the fragility of its ecosystems.

"In terms of pest control, the Hunuas really have been an outstanding success," said regional council biosecurity manager Steve Hix.

"It's the sort of thing that makes all the work seem worthwhile. Every year our job gets tougher, as there are fewer pests to find and thicker forest to walk through."