Lab breeds super-stoats

New Zealand scientists have bred stoats in captivity, for what is believed to be the first time in the Southern Hemisphere, in an effort to control the pest.

Stoats, ferocious predators scientifically known as Mustela erminea, are native to Europe, America and Asia, and were deliberately brought to New Zealand in the late 1800s to control rabbits, despite the protests of bird experts.

Now stoats kill up to 60 per cent of all North Island kiwi chicks and wreak havoc on other native bird populations.

Stoats are secretive and elusive, and are difficult to catch and study, according to the Department of Conservation, which pays Landcare Research to investigate ways to restrict stoat breeding.

Landcare scientists at Lincoln in Canterbury have bred two baby stoats, or kits, as part of their work to find out more about stoat life cycles.

DoC's stoat control research programme manager, Dr Elaine Murphy, said stoats had rarely been born in captivity, and the scientists had made a breakthrough. Pregnant female stoats had been brought into captivity a number of times, but had not given birth.

"We eventually want to breed our two kits on, to get the larger litters of eight or nine that stoats generally produce in the wild," she said.

A pest control and wildlife toxicology team leader at Landcare Research, Dr Cheryl O'Connor, the kits' official "auntie", said the youngsters were now about 7 weeks old, but were discovered only a fortnight ago.

"We left the mother alone for as long as possible, to minimise stress. Finally, we discovered the kits hiding in their nest.

"They are still cute, fluffy and weak like kittens, but when they reach their full weight of about 250g they will hiss and bite with the best of them."

Dr O'Connor said that what was so far known about stoat reproduction was fascinating: after mating in November or December, female stoats stored embryos for about nine months, until seasonal changes in hours of light and darkness triggered the embryos to implant in the uterus and start growing, and the infants were born about a month later.

Dr Murphy said: "We want to see if we can disrupt light and dark patterns to speed that process up, to produce more animals more quickly."

Once a captive population was built up, research could begin into restricting birth numbers through fertility control methods, to make the stoats' immune system react against its eggs.

The scientists would also look at treatments that might stop embryos implanting.

Dr O'Connor said many people did not realise what a menace stoats were in the wild.

- NZPA