Can African elephants use leaf colour as a visual cue when making foraging decisions?

Abstract

Finding food is one of the most important aspects of an animal’s life. Yet, locating it can be challenging as the availability and quality of food varies both spatially and temporarily. To overcome these challenges, mammalian herbivores may use spatial memory or senses such as smell and vision. Recent studies have found that African elephants (Loxodonta africana) use olfactory cues to locate food patches and to select plants to eat within these patches. However, the extent to which they may also use visual cues, such as those associated with leaf colour, a proxy for food quality, when making foraging decisions is unknown. To address this knowledge gap, we tested whether African elephants were able to discriminate differences in leaf colour (i.e., light green: high-quality new growth, dark green: lower quality old growth, brown: poor-quality senesced vegetation) over a range of distances (i.e., 3, 5, 10, 20, 40, 80 m). Testing four semi-tame elephants using visual-based choice experiments between different coloured canvases, we found that the elephants were able to discriminate colour differences at close range (i.e., ≤10 m), but not beyond. This suggests that when feeding within a patch, African elephants may utilise the visual cues associated with leaf colour to help locate high-quality food (e.g., individual trees, branches, and leaves) and thus increase their foraging efficiency. However, as they were unable to discriminate between the different colours over distances > 10 m, it is unlikely that they use colour when making long-range foraging decisions such as selecting feeding patches.