Threats to kiwi

Like much of New Zealand's wildlife, the kiwi evolved in isolation from the rest of the world for 65 million years until the first humans arrived 1000 years ago.

Long-lived and slow breeding, the kiwi and many other native species are no match for introduced mammals, armed with speed, a keen sense of smell enabling them to hunt at night, fast metabolisms and high rates of reproduction.

Dog (Canis lupus familiaris):

Tui, labrador-pointer cross

Whether it is a pig dog or a poodle, man's best friend is rarely a kiwi's. In parts of Northland in particular, as well as in Te Urewera, Wanganui, the Coromandel and Taranaki, roaming dogs are making huge dents in kiwi populations. The roamers may be pig dogs, pets, working dogs in rural areas, or dogs that have gone feral from lack of care and been forced to live off the land.

In the Northland Kiwi Sanctuary (managed for stoats), the average lifespan of kiwi is only 13 years, compared with more than 50 years in the Tongariro Forest Sanctuary, where there are few dogs. One roaming dog in Waitangi Forest killed an estimated 500 kiwi in six weeks.

Dog control would be easy in principle - keep them on a leash, tie them up, kennel them or fence them in when at home. But this is not an option for pig hunters, and a challenge in rural communities.

A growing number of pig hunters are taking their dogs through DOC-run kiwi aversion training schemes, but more study is needed to show how well the technique works.

Stoat (Mustela ermina):

Stoat

Introduced in the 1880s to control rabbits, this relative of the weasel and ferret predates juvenile kiwi up to 1kg. They can travel great distances, enter holes and burrows, and are now widespread throughout most New Zealand forests.

Trapping is the main form of control, usually using hen's eggs as bait, in a double trap laid every 150m-200m along lines 1km apart. Secondary poisoning can occur from eating rat and possum carcasses following 1080 poison operations. The baits need to be checked every two weeks in summer and less frequently in winter.

Feral cat (Felis silvestris catus):

Feral cat

There may be as many as 2 million cats in New Zealand. Our household moggies are the origin of the thousands of cats that have gone wild, either from dumping unwanted cats or encouraging stray populations, and these cats kill kiwi chicks. Control is extremely difficult because cats can range over several kilometres every night and trapping is the only method of capture at present.

Ferret (Mustela furo):

The largest relative of the stoat in New Zealand, the ferret or fitch is a particular problem in Northland, the Central North Island, Te Urewera, Taranaki and Wanganui. Ferrets' main prey are rats but if there are few rats, they may switch to attacking kiwi, including the smaller adult males.

Ship rat, Norway rat (Rattus rattus, R norvegicus):

Ship rat

Rats do not attack kiwi directly but they appear to compete for insect food and fruit. The issue has arisen in areas where there is good stoat control, because the absence of stoats allows rat populations to increase. The effect needs further research, and an opportunity will arise in Tongariro Forest in 2006/2007.

The Animal Health Board and DOC intend to air drop 1080 baits over the Tongariro Forest Kiwi Sanctuary to kill possums as part of bovine Tb control. The secondary effect on rats and stoats (from scavenging carcasses) and consequently kiwi chick survivorship in the temporary absence of rats and stoats will be measured.

Ship rat in fantail nest

People (Homo sapiens sapiens):

Unwittingly or not, one of the biggest threats to kiwi are human beings, through careless ownership of dogs, dumping unwanted domestic cats or ferrets, or bad luck in hitting a kiwi while driving. Leaving stoats to one side, the kiwi that have it the best in New Zealand are the ones that live far from humans.

Fortunately, more people are taking an interest in kiwi and are taking part directly in kiwi care projects, or indirectly via donations to Bank of New Zealand Save The Kiwi Trust. People are becoming increasingly part of the solution to kiwi decline.

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