Elephants would have had a hill to climb to cross Alps

Published on 25/07/2006 00:58

HANNIBAL must have had a hard job crossing the Alps, according to new research which shows that elephants hate climbing hills.

Scientists used global positioning system (GPS) satellite tracking to follow elephants across the African savannah.

They found that the animals studiously try to avoid sloped terrain. Even minor hills represent a major energy barrier.

An elephant needed to boost its calorie consumption dramatically to climb a hill - which meant finding a lot more to eat.

The researchers, led by Professor Fritz Vollrath of Oxford University, focused on the Samburu, Isiolo and Laikipia districts of northern Kenya, covering 32,000sq km, which are home to about 5,400 elephants.

They found that elephant population density dropped significantly with increasing hill slopes. The energy cost of trudging up hills was a likely explanation.

A 4,000kg elephant would need an extra 25,000 calories of energy for every vertical metre climbed - about 2,500 per cent of the cost of level walking.

"Climbing 100 metres would 'burn' 10,000 kilojoules, which would have to be either replenished by an extra half-hour of foraging, or paid for by using up body reserves," the researchers wrote in the journal Current Biology.

Megafauna such as elephants probably took a "rather different view of their surroundings" than did more lightweight animals, the scientists concluded.

"This is especially true if the heavyweights, like elephants, are herbivores, for which energy replenishment is so much more time- consuming than it is for carnivores," the researchers added.