By Tia Ghose
LiveScience

Nearly half of all of Africa's lion populations could face extinction in the next 40 years if conservation measures aren't changed, according to a new study.

The study, published Wednesday in the journal Ecology Letters, found that lion populations that were fenced into conservation areas rebounded in recent years, whereas lions in open preserves were challenged by prey loss and predation by human neighbors.

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"Lions in fenced reserves tend to do much better, they're achieving much better populations," said Luke Hunter, a conservation biologist with Panthera, an organization that works to protect endangered big cats. "It's also cheaper to achieve those outcomes."

Big cats
Lion populations have been shrinking — across Africa as they rub up against growing human populations. Herding cultures, such as the Maasai or the Zulu, may convert wild habitat to grazing land, thereby reducing the population of natural prey for the majestic cats. So instead of going after a zebra, lions will hunt people's livestock (and occasionally kill people).

"More and more people live in fairly rural areas where there is wildlife, but those people rely on livestock, so they're really coming into conflict often with lions," Hunter told LiveScience. "They just see them as a really dangerous enemy." [In Photos: A Day in the Life of a Lion]

To understand what strategies might best protect lions, Hunter and a few dozen colleagues analyzed lion population data from 42 sites across Africa. Some parks reported 46 years of data, whereas others had only three years of data.

They then compared the population trajectories with fencing, the money allocated to conservation and nearby human population density.

Fenced reserves cost a fourth of the cost to maintain and achieve the same results as unfenced reserves. Fenced reserves also had the highest lion numbers.

Unfenced lions, by contrast, faced attacks by neighboring people, poaching and declining prey populations.  Nearly half of the populations will dwindle to near extinction levels in the next 20 to 40 years if no conservation measures are taken, the study showed.

Don't fence us in
But while the fencing is incredibly effective for preserving lions, not every conservationist loves them, Hunter said.

"I would hate to see more of Africa fenced," Hunter said. "It just takes away from a sense of wilderness."

Fencing can disrupt the great migrations of herbivores and the movements of free-roaming animals such as the African wild dog or the cheetah, he said. But it may be the most effective way to save lions, he said.

"Whether it's a fence or some other form of barrier it's really clear that lions need physical separation from people if we're going to save them."

Follow Tia Ghose on Twitter @tiaghose. Follow LiveScience on Twitter @livescience, Facebook or Google+. Original article on LiveScience.com. 

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OSLO, Norway -- Animals living in patches of rainforest cut off from bigger expanses of jungle by farms, roads or towns are dying off faster than previously thought, according to an academic study published Tuesday.

"We uncovered a staggering rate of local extinctions," the British and Brazilian researchers wrote in the online science journal PLOS ONE.

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They visited 196 fragments of what was once a giant, intact forest in eastern Brazil on the Atlantic coast, now broken up by decades of deforestation to make way for agriculture.

Each isolated forest patch, ranging from less than the size of a soccer field to more than 12,000 acres, had on average only four of 18 types of the mammals the experts surveyed, including howler monkeys and marmosets.

White-lipped peccaries, similar to pigs, "were completely wiped out and jaguars, lowland tapirs, woolly spider monkeys and giant anteaters were virtually extinct," the British and Brazilian scientists said of their findings.

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'Bad news for conservation'
Normal estimates of declining wildlife numbers, based on the size of isolated forest fragments, predicted higher survival rates, it said. But they had underestimated continuing human pressures such as hunting and fires.

"This is bad news for conservation," Professor Carlos Peres, of Britain's University of East Anglia, told Reuters. Many animals had vanished even in what seemed big areas of forest with intact tree canopy, he said.

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The rate of species loss in the area studied -- the Atlantic Forest region which covers 95,000 square miles, the size of Britain or the state of Michigan, was likely to be mirrored in other countries such as Indonesia, Ghana or Madagascar, Peres said.

Plea for parks
The scientists urged better conservation.

In Brazil, animals survived best in five forest remnants that were protected as parks. "This paper is a very big positive endorsement of more protected areas," Peres said.

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Measures to place an economic value on forests could help, he said. Peres gave the example of preserving forests as part of a fight against climate change.

Forests absorb carbon dioxide, the main greenhouse gas, as they grow and release it when they burn or rot. Between 12 and 20 percent of man-made greenhouse gas emissions, most of which come from burning fossil fuels, are caused by deforestation.

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Almost 200 countries are looking into ways to protect forests through a U.N. program called REDD (Reducing Emissions from Deforestation and forest Degradation) that would put a price on carbon stored in trees in developing countries. One example would be to bring forests into carbon trading systems.

Peres said that "degradation" in U.N. jargon referred mainly to logging but should be expanded to cover threats to wildlife.

"My mission is to put wildlife and biodiversity into that second 'D' of REDD," he said.

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