Elephants' eating habits strongly influence lizards' habitat choices

Washington, January 29 : The eating habits of elephants have a strong influence on the habitat choices of lizards, says a researcher.

Robert M. Pringle of Stanford University says that his findings are based on an examination of the connections between elephants and lizards, for which he worked at the Mpala Research Center in Kenya between 2004 and 2007.

He observed that Kenya dwarf geckos (Lygodactylus keniensis) showed a strong preference for trees that had been damaged by browsing elephants (Loxodontia africana).

The researcher says that the local lizard population increased proportionally with the number of damaged trees, whereas lizards were virtually absent from undamaged trees in the same study area.

Upon further investigations, he came to the conclusion that the preference was due to hiding places that were incidentally created by the elephants' activities.

Pringle's findings are consistent with a relatively new concept of ecosystem engineering, the idea that activities of one kind of animal can create habitat for other animals.

The results also tender some support to the hypothesis that a habitat becomes more appealing to a larger variety of animals when engineers, like the elephants in this case, make it more complex. According to Pringle, this may indeed be the case in African savannas.

The researcher likens the way elephants "shake up" the savanna landscape to a tornado due to which trees and shrubs are splintered, cracked and fissured, and large branches are strewn all over the ground.

"The ripped up trees are like labyrinths compared to the pristine trees, which helps boost lizard densities," says Pringle.

He believes that lizards' preference to such habitats may be because the twisted crevices in the elephant-damaged trees give them shelter from predators and the harsh arid environment. It may also be because damaged trees provide suitable spots for female lizards to lay eggs.

A better understanding of the elephants' influence on their ecosystem is a particularly pressing need in this region. There are concerns in many parts of Africa that poaching may wipe out the large animals on lands where they are not strictly protected.

Pringle says that by gaining a better understanding of ecosystem engineering, and of the effects that large herbivores have on other species, may shed light on how the entire savanna ecosystem works.

"If you have no elephants, then you're missing this powerful source of disturbance, since their activities can provide other species with a chance to thrive. On the other hand, if you have too many elephants, then they can actually suppress the abundance of smaller animals by reducing their habitat and out-competing them for food," says Pringle

He believes that biodiversity may well be greatest in the middle ranges of elephant abundance.

Pringle's study has been published in the journal Ecology.

ANI