Less than 30,000 African lions remain in just 25 percent of their original natural habitat. ©Patrick J. Endres

“Good fences make good neighbors” is a mid-17th-century proverb, popularized by author Robert Frost in his 1914 poem “Mending Wall.” According to a new report published last week, that may just be the case—especially if your neighbors are lions.

In the next 20 to 40 years, it’s estimated that nearly half of Africa’s wild lion populations will reach near-extinction unless urgent conservation measures are taken. With fewer than 30,000 African lions remaining in just 25 percent of their original natural habitat, fencing them in—and fencing humans out—may be their best and only hope for survival.

But given lions’ need to hunt migratory prey, the high cost of fencing and our psychological need for wide, open vistas, is containing them the best solution?

Fences protect both sides of the line

A lion-proof fence is also elephant-proof, so a well-designed fencing policy would protect both. ©Eric Rock

Fencing has always been anathema to most conservationists and environmentalists. But in his new report published online in the scientific journal Ecology Letters on March 5, 2013, Craig Packer, a professor in the Department of Ecology, Evolution and Behavior at the University of Minnesota, concludes that both African lions and villagers would benefit from fences.

For the study, titled Conserving Large Carnivores: Dollars and Fence, Packer and his colleagues compared lion population densities and management practices across 42 sites in 11 African countries. The researchers found that conservation costs were lower and lion population sizes and densities were greater in reserves secured by wildlife-proof fences, compared to unfenced ecosystems. In the unfenced reserves, lions were subject to a higher degree of threats from human communities—including retaliatory killing by herders—habitat loss and fragmentation, and overhunting of lion prey.

In the fenced reserves, lions were maintained at 80 percent of their potential population capacity on annual management budgets of about $500 per square kilometer (0.39 square miles), while unfenced populations required an average of $2,000 per square kilometer each year to remain at just 50 percent of their capacity.

The offense of fences

Most African governments, however, don’t have the money to invest in expensive fencing projects. Fences can cost up to $3,000 per kilometer (0.62 miles) to install. Fencing around very large areas, such as the 17,000-square-mile Selous Game Reserve in Tanzania (a popular destination for African safaris), which is home to the largest remaining lion population in the world, would cost about $30 million. And that’s just the beginning of the obstacles a fence presents. If a small lion population is enclosed, let’s say, managers would need to ensure genetic diversity by introducing new animals every few years. And if the lions of a particular population make their living by pursuing migratory prey such as wildebeest, fences would be impractical.

Fences would be impractical for lions that pursue migratory prey, such as wildebeest. ©Patrick J. Endres

Some, such as one of the study’s co-authors, Luke Hunter of Panthera, a conservation organization based in New York City, believe that buffer zones to separate humans and lions or more kinds of conflict mitigation initiatives, rather than fences, should be considered. But while this particular approach has done well in Kenya, Packer says it is only feasible when lions are relatively scarce. Protecting core reserves and buffer zones for all lions would be more expensive than fencing. Nairobi National Park in Kenya is an example of an unfenced park where lions are doing relatively well, but such places must spend much more money. Antipoaching patrols and other management costs in unfenced parks can cost more than $2,000 per square kilometer per year while fostering only half the number of possible lions. In contrast, a fenced reserve can attain 80 percent of its maximum population density at a quarter of the cost. The difference could be critical for the future of lions; Packer’s study found that almost half of unfenced lion populations could plummet to less than 10 percent of their potential size over the next two to four decades.

In “Mending Wall,” Robert Frost also writes,

Before I built a wall I’d ask to know
What I was walling in or walling out,
And to whom I was like to give offense.

While the thought of putting more fences around Africa’s incredible wild areas is not pleasing to our psyches, we may have little choice. Whether by fencing or by some alternative physical boundary, such as intensely managed buffer zones, it is clear that separating lion and human populations will be essential for lions’ survival.

Do you think that conservationists need to accept the fact that the days of seeing a limitless vista of unspoiled African savanna are gone forever? As human communities expand, are fences now unequivocally necessary to protect African wildlife?

Here’s to finding your true places and natural habitats,