"Pringle's study," Jones said, "very clearly establishes the connection between the engineering activities of the elephants and the effects on lizards as being largely due to habitat creation."
Conservation Implications
The connection between geckos and elephants also has implications for the conservation and management of elephants, Pringle said.
"At the most basic level, these findings really underscore the importance of conserving elephants in particular," he said.
"They provide this crucial form of disturbance, and if you lose them, then you might well lose populations of other species in a cascade of extinction."
But determining how many elephants must be conserved is a complex calculation, Pringle noted.
His earlier work has shown that a heavy concentration of large browsers like elephants, gazelles, and giraffes tends to negatively effect the abundance of trees, beetles, and geckos.
When all large herbivores are excluded from a patch of land, geckos thrive, perhaps because the vegetation grows so thick and dense that it is full of hiding spots—similar to elephant-damaged trees.
A worrisome aspect of conservation management, Pringle noted, is that elephants are often excluded from small reserves like Kenya's Nairobi and Nakuru National Parks.
(Read related story: "South Africa Weighs Killing 'Excess' Elephants in Parks" [November 5, 2004].)
The new study underscores the need for some elephants, he said. The goal is to find the right balance—enough elephants to provide the benefits but not too many to outcompete other critters.
"There is probably a middle range of elephant density that is optimal from the perspective of overall biodiversity," Pringle said.
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