They say the kiwi is being killed at a rate of one every two hours and is "free-falling" to extinction.

A conservation report shows an 18% fall in the population in one of the kiwi's few remaining strongholds within a year.

The kiwi, thought to have evolved more than 30 million years ago, is a flightless, burrowing bird. It is the only bird known to have nostrils at the end of its beak which it uses to sniff out worms.

The population, made up of four different species, is now estimated to be 70,000 - down from five million in 1923.

Predators

Kevin Smith, director of the Forest and Bird Society which wrote the report, said the kiwi was under attack from predators at all stages of its life cycle.

Dogs and ferrets prey on adult birds, while stoats and cats are responsible for a 95% chick mortality rate. Possums and stoats also destroy kiwi eggs.

Mr Smith said if the rapid rate of decline continued kiwis could be wiped out on mainland New Zealand in as little as five years' time.

"The kiwi has all the hallmarks of a species heading for extinction," he added.

The kiwi has already vanished from parts of the north island.

Protection

The Forest and Bird Society has called for the government to commit NZ$10m (US$5.2m) to a kiwi recovery programme.

The society wants to establish about 10 zones to keep predators away from kiwis. It is also demanding an end to logging and clearing forests that provide key habitats.

The kiwi, which can live up to 40 years, is a one-off evolutionary design. Its habitat and lifestyle are in many ways more akin to that of a mammal.

Unlike most birds which rely on sight, the kiwi has a very strong sense of smell. It also has whiskers and fur-like feathers.

Kiwis live in monogamous pairs, but the sex roles are reversed with the females dominating the males.