By Traci Watson
Times are grim for the king of the beasts. Roughly 35,000 African lions roam the savannahs, down from more than 100,000 half a century ago, thanks to habitat loss, declining numbers of prey animals and killing by humans. One study estimated that fewer than 50 lions (Panthera leo) live in Nigeria and reported no sign of the animal in the Republic of the Congo, Ghana or Côte d’Ivoire.
Now a king-sized controversy is brewing over a proposal to shore up lion populations before it is too late. A prominent lion researcher has called for limiting conflict between humans and lions by erecting fences around reserves containing wild lions. The idea has split scientists, with those opposed to the idea arguing that fences could do more harm than good. The ensuing debate has also laid bare fundamental differences of opinion about how to preserve lions and other species, and raised concerns that a key challenge to lion conservation — lack of funds — is being ignored while scientists trade jabs about fences.
When he began the research that kicked off the furor, Craig Packer of the University of Minnesota in St Paul, who studies lions at Tanzania’s Serengeti National Park, intended to determine only the cost of conserving lions. But something more provocative emerged from his data. In work reported earlier this year in Ecology Letters, he and 57 co-authors calculated lion densities at 42 African reserves and found, Packer says, that the only variables that matter for density are “dollars and fence — nothing else”. He adds that “the fence has a very profound, powerful effect”, because it prevents lions from preying on livestock and people, meaning fewer lions are killed in retaliation. Packer would like to see fences around even some of the largest protected areas such as Tanzania’s 47,000-square-kilometer Selous Game Reserve.
But the paper triggered heated discussion, both online and at meetings, leading four months later to the publication of a response signed by 55 researchers. They argue that Packer’s analysis is wrong to use lion population density as its sole yardstick. By that measurement, they say, a dense population of several dozen lions in a small reserve is a success, whereas a large reserve containing 600 lions is a failure. When the authors restricted their study to lion populations whose density did not exceed the land’s capacity to support them and controlled for a reserve’s management budget, they found no relationship between fencing and density. More....