( but it only gave us a snapshot in time...)Predators keep the world green, ecologists find

"This article reports on the re-census," he added. "Indeed, during that five-year interval the populations of small, sapling-level plants continued to decline quite radically. And there's no question that the vegetation on these islands is just in a state of collapse."

A drought that began in 2001 and reached extreme levels in 2003 has now ended the study, Terborgh reported.

"By 2003, the lake level had dropped 26 meters," he said. "By then, I think only three of the islands were left surrounded by water. That ended the experiment because it allowed the animals to redistribute themselves in their own fashion. The overcrowded populations of the plant-eating animals that had been the object of our studies simply dispersed.

"The fundamental premise of the whole project was our ability to study predator-free space, and that condition was no longer met. In one period in 2003 we found six different predators on islands that previously had no predators."