Native small mammals on forest islands created by a large hydroelectric reservoir in Thailand faced extinction and a new paper says species living in rainforest fragments could be far more likely to disappear than was previously thought.
The authors draw parallels between logging and the islands created by hydroelectric power and say they were motivated by a desire to understand how long species can live in forest fragments. If they persist for many decades, this gives conservationists a window of time to create wildlife corridors or restore surrounding forests to reduce the harmful effects of forest isolation.
The researchers said they saw native small mammals vanish with alarming speed, with just a handful remaining – on average, less than one individual per island – after 25 years. "There seemed to be two culprits," said William Laurance of James Cook University in Australia. "Native mammals suffered the harmful effects of population isolation, and they also had to deal with a devastating invader – the Malayan field rat."
In just a few years, the invading rat grew so abundant on the islands that it virtually displaced all native small mammals. The field rat normally favors villages and agricultural lands, but will also invade disturbed forests.
"It was like ecological Armageddon," said Luke Gibson from the National University of Singapore, who led the study. "Nobody imagined we'd see such catastrophic local extinctions. The bottom line is that we must conserve large, intact habitats for nature. That's the only way we can ensure biodiversity will survive."
Citation: Luke Gibson, Antony J. Lynam, Corey J. A. Bradshaw, Fangliang He, David P. Bickford, David S. Woodruff, Sara Bumrungsri, and William F. Laurance , 'Near-Complete Extinction of Native Small Mammal Fauna 25 Years After Forest Fragmentation', Science 27 September 2013: 341 (6153), 1508-1510. DOI:10.1126/science.1240495