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1 July 2010 Fences are More than an Issue of Aesthetics
Morgan J. Trimble, Rudi J. Van Aarde
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Licht and colleagues (BioScience 60: 147–153) identify South Africa's pioneering efforts to reintroduce top predators to small, fenced protected areas as a conservation model America might be wise to follow. However, South African success at large predator reintroduction is largely the result of ubiquitous fencing that generally prevents predator conflict with people and livestock (see Gusset et al. 2008).

The consequences of applying a similar paradigm in America are not only aesthetic, as implied by Licht, but could also compromise the longterm success of biodiversity conservation. A recent review of fencing for conservation concluded that fencing is an acknowledgment that we are failing to coexist with and successfully conserve biodiversity, and that the costs—economic and ecological—generally far exceed the benefits (Hayward and Kerley 2009). Ecological costs include fence-line mortalities, influences on natural behavior, impingement on natural mechanisms of population control, restriction of animal movements in response to environmental changes (e.g., fires, climate change, drought), limitation of migration and genetic flow, and impediment to recolonization and source—sink population dynamics.

Licht and colleagues stated that there are relatively few concerns in South Africa about the fence around Kruger National Park. This is incorrect—there are serious ecological concerns including extinction debt and species persistence of many iconic herbivores, even though the park covers nearly 20,000 square kilometers (Nicholls et al. 1996, Ogutu and Owen-Smith 2003). Fences around smaller protected areas can be even more problematic.

References cited


M Gussett , et al. 2008. Efforts going to the dogs? Evaluating attempts to re-introduce endangered wild dogs in South Africa. Journal of Applied Ecology 45: 100–108. Google Scholar


MW Hayward , GIH Kerley . 2009. Fencing for conservation: Restriction of evolutionary potential or a riposte to threatening processes? Biological Conservation 142: 1–13. Google Scholar


AO Nicholls , PC Viljoen , MH Knight , AS van Jaarsveld . 1996. Evaluating population persistence of censused and unmanaged herbivore populations from the Kruger National Park, South Africa. Biological Conservation 76: 57–67. Google Scholar


JO Ogutu , N Owen-Smith . 2003. ENSO, rainfall and temperature influences on extreme population declines among African savanna ungulates. Ecology Letters 6: 412–419. Google Scholar
Morgan J. Trimble and Rudi J. Van Aarde "Fences are More than an Issue of Aesthetics," BioScience 60(7), 485-486, (1 July 2010).
Published: 1 July 2010

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