Australasian Science: Australia's authority on science since 1938

Are Two Fences Better Than One?

By Kate Helmstedt

Conservation fences are very effective in allowing threatened animals to breed, but when the population grows too much, managers must decide between extending the existing fence or building a new enclosure.

Kate Helmstedt is a researcher with the Environmental Decisions Group. She is based at the University of Queensland.

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Fences are a key strategy in the conservation of threatened native species. Australia has more than 37 large conservation fences enclosing 27 species of bird, marsupial and reptile in more than 35,000 ha of predator-free habitat. On the Australian mainland, many of these species can no longer be found outside chain-link and electrified wire.

These species are perfectly adapted to the Australian environment but have been driven to the brink of extinction by cats and foxes. Once they’re protected behind a fence from these predators, their numbers can increase dramatically. That’s great, but this positive outcome creates its own problems. What happens once the population overshoots the carrying capacity of the fenced area?

Fence managers often decide to build upon success and secure funding for another fence. There are two basic ways this new funding can be spent. They can either expand the existing fence or build a second enclosure.

The Arid Recovery project at Roxby Downs in South Australia used the first strategy. The Mount Rothwell biodiversity reserve outside Geelong in Victoria is applying the second option.

Both options have benefits. For a given amount of money, a fence expansion can add much more land than a whole new fence. That means more protected habitat per dollar of budget, and more protected animals.

On the other hand, an...

The full text of this article can be purchased from Informit.