Fences May Cause 'Ecological Meltdown' of Wildlife
Wildlife fences are constructed for a variety of reasons including to prevent the spread of diseases, protect wildlife from poachers, and to help manage small populations of threatened species. Human—wildlife conflict is another common reason for building fences: Wildlife can damage valuable livestock, crops, or infrastructure, some species carry diseases of agricultural concern, and a few threaten human lives.
At the same time, people kill wild animals for food, trade, or to defend lives or property, and human activities degrade wildlife habitat. Separating people and wildlife by fencing can appear to be a mutually beneﬁcial way to avoid such detrimental effects. But in a paper in the journal Science, published April 4th, WCS and ZSL scientists review the 'pros and cons' of large scale fencing and argue that fencing should often be a last resort.
Although fencing can have conservation benefits, it also has costs. When areas of contiguous wildlife habitat are converted into islands, the resulting small and isolated populations are prone to extinction, and the resulting loss of predators and other larger-bodied species can affect interactions between species in ways that cause further local extinctions, a process which has been termed "ecological meltdown".
"In some parts of the world, fencing is part of the culture of wildlife conservation — it's assumed that all wildlife areas have to be fenced. But fencing profoundly alters ecosystems, and can cause some species to disappear.
In addition to their ecosystem-wide impact, fences do not always achieve their specific aims. Construction of fences to reduce human—wildlife conflict has been successful in some places but the challenges of appropriate fence design, location, construction, and maintenance mean that fences often fail to deliver the anticipated benefits. Ironically, in some places, fences also provide poachers with a ready supply of wire for making snares.
Co-author Simon Hedges of WCS said: "A variety of alternative approaches — including better animal husbandry, community-based crop-guarding, insurance schemes, and wildlife-sensitive land-use planning — can be used to mitigate conﬂicts between people and wildlife without the need for fencing. WCS projects working with local people and government agencies have shown that human—elephant conflict can be dramatically reduced without using fences in countries as different as Indonesia and Tanzania."
Co-author Sarah Durant of ZSL's said, "An increased awareness of the damage caused by fencing is leading to movements to remove fences instead of building more. Increasingly, fencing is seen as backwards step in conservation."
Continue reading at Wildlife Conservation Society.
Savannah fence image via Shutterstock.