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.