Barriers, the Beef Industry and Unnatural Selection: A Review of the Impact of Veterinary Fencing on Mammals in Southern Africa

Abstract

Thousands of kilometres of veterinary fences crisscross southern Africa, dividing habitat and blocking the movement of terrestrial animals, and hundreds of kilometres of new fences are proposed or under construction. Although the primary targets of these fences are livestock and wild ungulates carrying diseases that could threaten livestock, the fences are not selective and create substantial physical barriers for many wildlife species. The ecological cost of these fences is often overlooked, but the evidence from 34 published and unpublished reports amounts to significant ongoing damage ranging from loss of life to the disappearance of entire migrations. Fences have adverse effects on wild mammals at the individual, population and species levels, and alter community structure and ecosystem productivity. They disrupt individual daily movements and may lead to death by starvation, dehydration or entanglement. Fencing can divide populations, prevent recolonisation and render sub-populations prone to the risks faced by small populations. Large-bodied, migratory ungulates and elephants Loxodonta africana have been the most severely affected. Fences can worsen negative interactions between people and wildlife: examples show that fences facilitate poaching and that fencing which disrupts the movement of large mammals, especially elephants, can increase conflict with local people. In light of current challenges (especially climate change) and opportunities (e.g. restoring degraded areas or reconnecting conservation areas), fences should be considered carefully for their role in impeding or altering events essential to species persistence, like dispersal, seasonal movement and range expansion.