A local sanctuary is disputing claims predator-proof fencing is expensive and ineffective.
Two recent national reports described predator-proof fences as unsustainable, expensive and a stop-gap measure.
Author and Canterbury Museum vertebrate zoology curator Paul Scofield wrote: "The creation of these sanctuaries enclosed by predator-proof fences often creates small, expensive zoos surrounded by
degraded habitat that will never be able to sustain the animal and plant species contained within the fence."
The annual cost of maintaining fenced forests was calculated at $3365 per hectare, compared to $29 per hectare for maintenance of the Little Barrier Island sanctuary.
A study led by University of Auckland ecologist Bruce Burns was more positive.
It indicated fencing played an important role in New Zealand's conservation strategy, in practice and as an advocacy tool.
But his article also said protective fences were only stop-gap measures. "The ultimate [and currently unrealistic] measure of conservation success will be when the threat is removed outside the fence, and the fence itself can be taken down."
Cape Kidnappers-based Cape Sanctuary has more than 10km of fencing around 2500ha of coastal land.
Sanctuary ecological advisor John McLennan said it was good people were debating the value of sanctuaries but many of the criticisms did not apply at the local level.
Dr Scofield was referring to small sanctuaries and Dr Burns was positive about the important role played by fencing in NZ conservation, he said.
"Cape Sanctuary is the largest mainland sanctuary of its type in NZ so takes advantage of economies of scale and the help of many volunteers," Dr McLennan said. "The sanctuary is also very focused on saving threatened species from extinction and on restoring natural habitat, both of which, to date, have achieved good success."
The costs estimated by Dr Scofield were "well off the mark" for Cape Sanctuary, but may be based on small-scale projects.
The ideal put forward by Dr Burns to remove all threats outside the fence was unrealistic and unless private land owners were prepared to support the Department of Conservation by investing in such fenced sanctuaries New Zealand's conservation strategy would be even more at risk.
"In our view, to argue about the cost-benefit of wildlife sanctuaries misses the point made by Dr Burns - that, even as a stop-gap measure, fencing plays a key role in New Zealand's conservation strategy. We consider Cape Sanctuary to be very cost-effective, well-maintained and sustainable."
The chairman of Auckland-based Tawharanui Open Sanctuary Stephen Palmer had suggested the figures in Dr Scofield's report may have been based on capital costs, rather than maintenance.
Additional reporting APN
