Elephants, like humans, also carefully plan their journeys.

When we travel, we usually carefully plan our journeys and choose the route we will follow to find the fastest, most comfortable, cheapest, or most scenically attractive, depending on our priorities. We are not the only species that makes periodic movements. Many other animals, such as herbivores that live in social groups, also do so in search of the best pastures and water sources depending on the time of year. This is the case with zebras, wildebeests, and gazelles, among many others. It may seem that they move guided simply by their survival instinct, without giving it much thought, but as Emilio Berti and his collaborators from the German Centre for Integrative Biodiversity Research, the Friedrich-Schiller University of Jena, the University of Oxford, and also the organization Save the Elephant have just demonstrated, they are guided by their movements.

As published in Journal of Animal EcologyAfrican elephants don't move randomly in search of food and water, but rather select the routes they follow using their own criteria: saving energy. It's a strategy that can be somewhat compared to the one birds use when they take advantage of the thermal updrafts generated in the atmosphere when there are temperature differences to rise and fly with less effort. In this study, researchers analyzed GPS tracking data from 157 African elephants, collected over 22 years, between 1998 and 2020, by Save the Elephants, a research and conservation charity for these large mammals based in Nairobi, Kenya.

Energy landscapes

For their analysis, they used an innovative modeling method called ENERSCAPE, which allows them to assess the energy costs of movement based on body mass and terrain gradient. They also used a statistical approach called step selection function, which compares the locations elephants have actually visited with other similar nearby areas they could have chosen but hadn't. By integrating these estimates with data on vegetation productivity and water availability obtained through satellite imagery, they constructed detailed "energyscapes" that help explain what criteria elephants use when deciding where to move and which route to follow. The concept of an energyscape refers to the availability, distribution, and access to natural resources within a territory, as perceived and utilized by an animal species, taking into account energy gains and losses for survival and reproduction.

Tracking the routes elephants follow within these energetic landscapes has shown that 94% of elephants avoid steep and rugged terrain and prioritize flat routes without topographical difficulties, as they entail lower energy expenditure. This indicates that they not only know and remember the environment and the routes they follow, but also the environment itself, allowing them to make decisions based on the best balance between costs and benefits to choose the most energy-efficient paths.

Furthermore, 93% of elephants actively select resource-rich environments—that is, areas with higher vegetation productivity. They also take the presence of water into account, but in this case, researchers have observed individual variations, reaffirming that their route-based decisions are based on self-awareness. Some prefer to stay close to water sources, while others choose to travel further away, demonstrating that their choices are more complex than simply heading to the nearest river or pond.

A balance between effort and speed

Travel speed also influences their choice of route. When traveling quickly, 93% avoid difficult terrain, a percentage that drops to 74% when traveling slowly and more leisurely. This suggests that, when choosing a route, they carefully consider the balance between the effort required and energy efficiency, especially during long journeys.

As these researchers note at the end of the paper, these discoveries have direct applications for wildlife conservation and could help guide the design of protected areas and migration corridors. Rational, the empirical demonstration of these facts emphasizes the importance of taking into account the decision-making processes animals make, whether they do so with a certain level of awareness or instinctively, in order to increase the efficiency of conservation projects.