Kiwis for Kiwi - Kiwi Facing Extinction

Scientists estimate that before people arrived in Aotearoa, 12 million kiwi lived in the native forests, sand dunes and shrublands of the North, South and Stewart Islands. By around 1920 kiwi populations had dropped to around 5 million birds. Today they have plummeted to a total world population of 50-60,000 birds. This means over the past one thousand years the kiwi population has declined by 99.5%.

Remaining kiwi populations are disappearing at a rate of 6% each year, halving approximately every decade. However, there are considerable variations - the Urewera population is reducing about six times faster than populations near Whangarei in Northland.

The situation is urgent. All mainland species of kiwi are threatened with extinction unless the causes of the decline are addressed. Based on present trends, kiwi could be extinct on the mainland in about fifteen years - with the exception of five DoC kiwi sanctuaries and community 'kiwi care' efforts. Kiwi are already extinct in many areas, such as the Manawatu, Wairarapa, Horowhenua, Marlborough and most of Canterbury and Otago.

There is a 3-6 year window to choose which remaining kiwi populations we save and which we allow to become extinct. Unless the survival rate improves, the kiwi's decline will accelerate as existing adult kiwi age and die.

Populations without extensive predator control do not produce enough chicks to replace the old kiwis as they die of old age.

The Barrier

All the evidence identifies a shortage of money as the single most important barrier. Saving the mainland kiwi is, therefore, a political matter. Conservation management is a long-term business. There is little point preparing a ten-year plan to save the kiwi if the money to do so is not available. Parliament has a duty to allocate sufficient money for the well being of the kiwi.

Cost of Saving Kiwi

Because of different terrain and other variables, the cost of operating 12 kiwi sanctuaries will be in the range of $20 to $50 per hectare per year - a total cost of around $110 million annually. At the same time there is an urgent need for more research on finding better ways to control stoats, cats and ferrets.

Intensive kiwi control over 200,000 hectares will have multiple benefits as other endangered species thrive in kiwi sanctuaries including kaka, whio/blue duck and kukupa/kereru, whose survival is critical for forest health and regeneration. The present kiwi sanctuaries throughout the country are mostly in public ownership as National Parks or conservation areas and are managed by the Department of Conservation, sometimes in conjunction with local community groups.

Information on kiwi and pest control has been gathered through the Kiwi Recovery Program sponsored by the Bank of New Zealand, the work of Landcare Research, community conservation groups, DoC's Mainland Island Program and others working in the field of kiwi recovery.

The Government needs to strongly invest in a range of tools to protect kiwi: in research and development, in local community partnerships and to target other significant kiwi populations, such as those in Whanganui National Park. This area has the highest numbers of kiwi outside Stewart Island. Around 10,000 North Island brown kiwi live there and DoC has no specific programme aimed at saving these kiwi.

Chick Mortality

Chick mortality is a key issue. Research identifies a kiwi's first year as the most vulnerable period, when stoats and cats kill about 95% of juveniles.

Population decline would cease if about twenty per cent of young kiwi survive to adulthood. Kiwi can bounce back from this base as they live for about thirty years and can lay up to 100 eggs in a lifetime.

Adult Mortality

Dogs, ferrets, possum traps, cyanide poison (used for killing possums), vehicles - and perhaps wild pigs - are the major threats to adult kiwi. The impact of ferrets and dogs on adult kiwi in mainland forests is unpredictable and episodic; both can cause massive and rapid reductions in localised populations. Taborsky, an Austrian scientist, documented an episode in Waitangi Forest (1988) where a single dog killed about 500 kiwi in a few months. This is not an isolated incident.

Dog Control Needed

The absence of effective dog control is a major threat to adult kiwi where kiwi live close to human settlements or in areas where dogs accompany people hunting and tramping. Of a reported 194 kiwi deaths in Northland, there is documented evidence of 130 cases of dogs killing kiwi - feral dogs, wandering pets, farm dogs and hunting dogs. Dog control plans need to developed by the Department of Conservation.

Habitat Loss

Roller crushing bush, vegetation clearance and burning of scrub habitats continue to threaten some kiwi populations. Habitat loss concentrates predators into the remaining habitat and affects the social organisation of kiwi. Habitat alteration by deer and goat browsing affects kiwi by making native forest more open and accessible to predators. Adult kiwi rarely remain for more than a few years in forest remnants in agricultural landscapes, presumably because of predation by dogs and ferrets.

Predator Control

A solution would see a range of cost-effective tools combining aerial and ground applied 1080, community initiatives and intensive trapping of stoats and rats.

This page was updated on 4 June, 2008