It seems counter intuitive don’t you think? Putting a fence around wildlife, containing and restraining what is by definition not tameable. Yet fences are normal, accepted. Reserves, conservation areas and national parks are defined by this man made boundary and can only operate because of them.
This is because fences are useful. They keep two dangerous and uneasy neighbours apart: humans `and wild animals. Wildlife can cause damage, especially when humans and animals want to occupy the same zip code. They can introduce disease, eat and destroy livestock and crops and threaten human life. In the same way humans can cause damage. We degrade wild land, kill wildlife for food, for trade, and to defend and protect our land and on occasion, even our lives. Fences then, would seem mutually beneficial.
But there are more specific ecological reasons for erecting fences. Endangered animals that need to be preserved are often fenced as a last attempt at conservation and as protection from poachers. Fences also separate endangered species from predators and protect native species from invasive ones. Preventing collisions on the road and disease transmissions between species, as well as securing animals as a commodity (for wildlife hunting) are also important reasons to fence. The costs and ecological consequences associated with fencing are however great and very necessary to discuss.
Fencing by definition is creating a boundary, it is fragmenting a habitat and preventing movement and connectivity across a landscape. Animals are also trapped within a confined space, which alters interactions. Predator numbers are often lower in enclosed spaces, which can increase prey numbers and profoundly alter the food web. This in turn can lead to the local extinction of individual species. The environment and land itself also changes. The grazing it needs to support is much higher because animal movement across large areas has been shut down. This leads to changes in the vegetation and a decrease in wild herbivores that are dependent on the vegetation for food.
This is intensified with climate change because as habitats are changing and shifting, animals can’t shift and adjust with them. The fence itself poses a threat to wildlife. Poachers often modify the wire to create snares and predators can even change their predation techniques by chasing their prey into fences and trapping them. In turn, park rangers and managers, see the predators as threats/pests and remove them from the enclosed space.
Compounding the costs, are the practical challenges that exist when constructing fences. Design, location and maintenance, to mention some. Once the challenges are overcome, one might also find that these boundaries fail to deliver the benefits that are expected. They don’t always act as an efficient barrier to determined poachers and sometimes also fail to prevent large animals from breaking through them. In southern India for example, 49% of fences fail to prevent elephants from passing through them.
We understand that the function of fences is necessary, but are there alternative approaches that might not have such extensive impacts? Turns out there are. Human/Wildlife conflict can be managed through alternate methods of herding, grazing, crop guarding and wildlife sensitive land use planning. One might also prevent disease spread through vaccinations. Using virtual fences, such as scent marks to constrain African wild dogs is effective but expensive and labour intensive.
Fences are an ‘easy fix’. Once constructed, one often feels like the problem has been solved. This article reviewed does a good job at discussing why this is often not the case, why fences often create more problems than they solve. The intricate balance of ecosystems is compromised by the erection of fences and this article concludes by stating that they should be a last resort in the conservation effort.
Fences are however not always the last resort and in some situations can be the better solution. An example close to home exists. Baboons on the Cape Peninsula of South Africa are in conflict with humans, as these animals have adapted to utilizing food, waste and shelter that is provided by people. In turn they are aggressive, destructive and dangerous. In this particular situation, the pros of fencing have outweighed the cons as an effective management tool.
Fencing is a traditional and accepted method of management and conservation. But with altering climate causing habitats to change, it is important that we start to think of other more suitable options for conservation. We need to ensure that we don’t try and contain or save one species at the detriment of an entire landscape.
This review is based on: Woodroffe,R. et al. 2014. To Fence or not to Fence. Science 344 (46)