The researchers say that while the elephants might avoid hills to avoid risks such as overheating, injury, lack of water or unsuitable vegetation to eat, they are more convinced that energy considerations are a major factor.
They estimate that in climbing, a four tonne elephant uses 40 times as much energy than it does in walking. Muscle efficiency also has to be taken into account, and so they estimate that an elephant climbing a hill versus walking costs an elephant about 2500 percent more calories.
Based on how much food an elephant eats each day in its 16-18 hours of foraging, they estimate that to climb 100 metres an elephant would have to spend an extra half hour each day eating, explaining why elephant prefer not to climb hills.