Scott Halleran / Getty Images
A marmoset hangs off a tree on May 6, 2012, during the LPGA Brazil Cup at the Itanhanga Golf Club in Rio de Janeiro. Marmosets were among the animals surveyed in the study of eastern Brazilian forests published in PLOS One.
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.
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.
'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.
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.
Mario Tama / Getty Images
The Belo Monte dam is among 60 Brazil plans to build in its Amazon region to help power its growing economy. But the vision also has its critics.
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.
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.
Mario Tama / Getty Images
The Amazon rainforest has meant prosperous times for many in Brazil, but environmental and cultural disaster for others.
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.
More world stories from NBC News:
- 1,000 suicides linked to hard economic times in Britain?
- Dozens killed in Afghan suicide bomber attacks
- Study: Japan nuclear disaster caused mutated butterflies
- Restaurateur claims Games cost her business $140,000
- On to Sochi: Virtual tour of the next Olympic city
- Will world inaction help al-Qaida gain foothold in Syria?
- Analysis: Egypt's Morsi shows he's a force to be reckoned with
- Vatican says the 'butler did it,' orders trial
- Olympic heroes turn tourists as London 2012 end nears
- Mormon church brings in $7 billion a year from tithing