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© Daryl Balfour/NHPADo elephants make other creatures feel safe at water holes?
Are elephants the bullies of the national parks? Should they be culled to give other creatures a look-in at the water hole?

These are questions that were asked recently when figures showed that, as some elephant populations have increased due to reduced poaching and creation of artificial water holes, other herbivore species have declined.

But when Marion Valeix, then at the National Centre for Scientific Research in Beauvoir-sur-Niort, France, set out to discover if the elephants of Hwange National Park in Zimbabwe were harming other herbivores by chasing them away from water holes, she got a surprise.

Her team found that members of nine herbivore species (including buffalo, zebra, warthog and wildebeest) rarely backed off when elephants were around. Instead, all herds increased their drinking time - normally between 5 and 10 minutes - by around 2 minutes.

Valeix says elephants may make other herbivores feel safe from predators. "I have seen lions approach to hunt buffalos at a water hole and retreat when a group of elephants came closer and surrounded the buffalos," she says.

Big browsers

Alternatively, the herbivores may take longer to drink because they spend time looking out for the elephants, feeling nervous about them.

"We will have to study the time individual animals spend drinking compared to looking around to answer this question. But even if there is increased vigilance towards elephants, the time difference is so small that it is unlikely to explain herbivore population declines," says Valeix.

Community ecologist Todd Palmer at the University of Florida, who studies the interaction of elephants with other species, argues that the water holes themselves may be to blame for the herbivore decline, because they help sustain artificially high densities of animals.

"Elephants are very water dependent and incredibly damaging to the landscape - they eat trees," he says. "As a result, there may be a decline of herbivore species that browse trees."

Journal Reference: Biodiversity and Conservation (DOI: link)