A Landcare Research scientist is urging those who carry out rabbit poisoning programmes to consider also getting rid of the feral cats that feed on them.

In an article published in a recent Landcare newsletter, wildlife ecologist Dr Al Glen said rabbits "should not be controlled in isolation".

"Rather cats should be controlled at the same time."

Dr Glen's comments echo those of Wellington philanthropist Gareth Morgan who has caused controversy with his calls to kill stray cats to protect native birds.


He and his colleagues from the Crown-owned research institute have been involved in counting rabbit and feral cat populations in Otago and the Mackenzie Basin.

The study confirmed rabbit numbers contributed to "inflated numbers" of feral cats - and a consequence of increased cat numbers was added pressure on native species.

Otago Regional Council announced this week that poison needed to be laid on 8000ha of rabbit-prone land in the Wanaka area but said there were no plans to target cats because they were not a declared pest.

While his study showed cat numbers declined as rabbit numbers went down, Dr Glen warned in the newsletter "some caution" was required when reducing rabbit numbers suddenly.

"Sudden reductions in rabbit numbers can increase predation on native species in the short term. Faced with a shortage of rabbits, cats may simply eat more native prey.

"Because such prey are generally less abundant than rabbits, cat numbers will eventually decline, but not before they have eaten many native animals."

He considered that by targeting both rabbits and cats simultaneously, both species "can be suppressed over large areas for long periods".

"This should have considerable benefits for pasture and for native vegetation and fauna."

Dr Glen said it was expensive to target feral cats and the need to control them depended on whether native species needing protection were present.

"We certainly hope that people like regional councils will ... at least consider the idea.

"Whether that does realistically lead to them changing the way they do things is another question."

Mr Donaldson said cats ate freshly poisoned rabbits and that helped control their numbers.

"I don't believe that feral cats will be a major concern requiring separate control in the rural Central Otago environment in the near future.

"But council staff will continue to monitor the presence of cat and ferret populations."

Dr Morgan said New Zealand has one of the highest rates of cat ownership in the world, with about 46 per cent of households owning one or more cats.

He wants owners to keep their cats indoors or microchip them. Strays found without chips should be euthanised, he said.