Laurie Collins: careless interference into Nature’s ecosystem can be disastrous.

Special report via Tony Orman

Invariably interference by Man into natural ecosystems is disastrous says the Sporting Hunters Outdoor Trust.

Trust spokesman Laurie Collins of the West Coast was commenting on a current controversy over wild cats. “Recent statements displaying a hatred of cats are wide the mark ecologically, whether the felines are domestic or wild. Cats are killers as any predator is. But they kill only for their needs, i.e. food. It’s no different to any predator -– Man included. They kill,” he said. Laurie Collins has had a wide experience in pest work. Initially as a young forestry trainee about 1958, when he worked on the first trials of 1080 poison in the Caples valley at Lake  Wakatipu and then subsequent “pest” work with the Forest Service and regional councils. In addition he has had a life-long love of the wilderness recreationally. “Removing a predator from a food chain invariably has adverse effects. A classic case was Macquarie Island, south of Tasmania. a rainy, windswept place teeming with wildlife. But things changed due to Man’s interference,” he explained.

The changes began with the extermination of the feral cats between 1985 and 2000 in an attempt to restore the island and its bird population to its pristine state. Once cats were eliminated, there followed an explosion in the rabbit population. The feline predators had been removed from the food chain. Primarily the cats were keeping the rabbits in check.


The explosion of rabbits devastated the island as copious tussock grasses which consolidated the steep slopes were almost entirely denuded. This result was a loss of habitat for nesting birds and an increased number of landslides. “You’d think people might learn from past mistakes because way back in 1867 the New Zealand weka was introduced as a source of food,” said Laurie Collins.  Then weka put pressure on native Macquarie Island parakeet and rail, and the two species became extinct on the island. With less food weka numbers then declined plus  killing of them towards the 1980s and the last weka was killed in 1988.

Feral cats had been recorded on the island way back in 1820. Everything was in equilibrium ecologically.

Same with 1080

Laurie Collins said 1080 poison in New Zealand used extensively by the Department of Conservation was a similar example of ill-advised interference. “It’s the same with 1080 poison in New Zealand. 1080 aerially spread for rats, knocks them back, to a low percentage  with 10-15% off the rodents surviving. But rats are superbly prolific breeders.  Eighteen months after 1080, the rats have bred back to pre-poison levels.  Three years after poison the rat numbers are three to four times original numbers – a super plague of rats. Then the main predator of rats, stoats with abundant food, spiral upwards in a big population increase”. He said the rat explosions following 1080 aerial drops was in a Landcare Research study 2007.

The adverse effects of 1080 did not end there, as with greatly increased rat numbers, stoats whose main prey is rats and with more food, soared in numbers too. “All DoC and Ospri have achieved is population explosions of rats then stoats,” he said. “That’s why every four years or thereabouts, another poison drop has to be made. You’d think DoC would know better since it’s documented in Landcare Research work.”

Careless, thoughtless interference into Nature’s food chain equilibrium is invariably counter-productive and disastrous said Laurie Collins who added caution and thought are needed.