A pest-exclusion fence is a barrier that is built to exclude certain types of animal pests from an enclosure. This may be to protect plants in horticulture, preserve grassland for grazing animals, separate species carrying diseases (vector species) from livestock, prevent troublesome species entering roadways, or to protect endemic species in nature reserves. These fences are not necessarily traditional wire barriers, but may also include barriers of sound, or smell.[1]
Animals can be excluded by a fence's height, depth under the ground and mesh size. It is also important to choose a construction material that cannot be climbed; furthermore, sometimes it is necessary to create a subsurface fencing element to prevent burrowing under the fence.[2][3] Fences are usually designed with the target pest species (the species to be excluded) in mind, and the fences are made to effectively exclude those species. This results in a wide variety of designs for pest exclusion fences (see examples below). Often the fence is encircled in electric wire to ensure that animals can not climb over the fence.
Australia has utilised exclusion fencing since the 1860s.[6] The most well known exclusion fences in Australia are the barrier fences. Barrier fences are long (usually linear) barriers erected for the purpose of excluding particular species from large portions of Australia. The most well known barrier fences are the Dingo Fence and the Rabbit-proof fence, but there are many others.
In more recent years, pest-exclusion fences have been built around singular properties, or groups of properties.[7][5] This practice is known as cluster fencing.[7] Cluster fencing allows farmers to monitor and mitigate predation pressure on livestock, and monitor Total Grazing Pressure (TGP) through accurate abundance data of native, pest, and domestic herbivores.[5]
Australia uses pest-exclusion fencing to separate several high-value or threatened species from introduced predators. One such example is Arid Recovery in South Australia, where feral cat, red fox and rabbit have been removed for the conservation of 5 threatened species.
Prior to human settlement New Zealand had no land-based mammals apart from three bat species. The introduced mammal species, such as rabbits, deer, and possum, have since caused huge ecological changes to the biota of New Zealand. Pest-exclusion fences are increasingly used for conservation of indigenous species by excluding all mammals.
Locations of predator-proof fences include:
Deer-proof fencing was used in Nagano Prefecture, Japan in a conservation effort to maintain plant diversity. The methods were effective for increasing species richness, but not as effective for conserving rare plants.[8]