African elephants are avid walkers, says Bouwman. ‘Elephants typically use a habitat of around 2,000 km² per month. That is roughly the same size as the Dutch province of Limburg. They walk about 140 kilometres per month.’ But that changes when conditions worsen: during short droughts (a month), elephants cover less distance than normal.
Trackers
Bouwman used data collected over 19 years from trackers around the necks of elephants living in Botswana. ‘That does not affect the behaviour,’ explains the biologist. ‘In the first week after being fitted with a tracker, they display slightly unusual behaviour, but after that they move around just as much as before.’
Bouwman observed that during short-term droughts, the elephants stayed close to rivers and lakes. They ventured less often into areas inhabited by people. ‘But if the drought lasted a year, the elephants moved away from rivers and lakes and came closer to human settlements. After a year, rivers may dry up, forcing the elephants to seek alternatives.’
The search for alternatives during prolonged droughts leads to more human-wildlife conflict. ‘If an elephant enters a field in search of food, it can be fatal for both humans and animals. Elephants take greater risks when drought persists.’
Climate change
Bouwman says: ‘What we have demonstrated is that the duration of a drought matters. If we see that a drought is continuing, it may be wise to take appropriate measures, such as erecting fences or installing additional waterholes for elephants in strategic locations.’
Droughts are becoming increasingly common, particularly in southern Africa, says the biologist. ‘We still know relatively little about animal behaviour during droughts. We hope this study can contribute to protecting wildlife from the effects of climate change.’