Where Elephants Tread, Geckos Thrive, Study Finds

February 1, 2008

As elephants bash and browse through the trees of the African savanna, they create nooks and crannies for little geckos to hide from predators and the hot sun, according to a new study.

The research shows that the population of Kenya dwarf geckos increases proportionally with the number of trees with limbs snapped, trunks split, bark stripped, and branches fallen in the wake of an elephant run-in.

African bush elephants, which weigh more than 15,000 pounds (7,000 kilograms), are known to modify habitats dramatically, noted Robert Pringle, an ecologist and conservation biologist at Stanford University in California.

Usually, he added, the modification is considered a destructive force.

"But here I seem to have evidence that they can also be a constructive force, with positive effects on the abundance of other species and perhaps on biodiversity more generally," Pringle wrote in an email from Kenya.

The damage caused by elephants creates crevices in broken trees, as well as a cover of strewn branches, providing geckos with secure spaces to rest or lay eggs, he explained.

Pringle conducts his research at the Mpala Research Center in central Kenya. He explains the positive effect of the elephant browsing on gecko population in the January issue of the journal Ecology.

Ecosystem Engineering

The finding is a "very nice demonstration" of ecosystem engineering, said Clive Jones, an ecologist at the Cary Institute of Ecosystem Studies in Millbrook, New York.

Ecosystem engineering is the process by which the activities of one kind of animal can structurally modify habitats of another, potentially benefitting other species. Jones and his colleagues first introduced the concept in 1994.

Jones said that many examples of ecosystem engineering have been based on inferences.

For example, if a beaver pond is full of salamanders not found anywhere else, the inference is that the beavers' modification of the habitat benefits the salamanders.

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