Wind conditions do not consistently affect large-scale movement decisions of large savanna herbivores

Abstract

To decide where and when to move, animals combine memorised information with environmental cues. Wind speed and direction can affect the way animals perceive the environment by reducing the detection and shaping the spatial distribution of sensory cues. Although these cues are expected to be used for forage localisation and predation avoidance in large herbivores, for instance, we still do not know to what extent wind can ultimately influence their large-scale movement decisions. To tackle this knowledge gap, we used GPS data from four species of large African herbivores experiencing contrasted predation risks (blue wildebeest, Connochaetes taurinus, plain zebras, Equus quagga, African buffalo, Syncerus caffer, African elephant, Loxodonta africana), in multiple protected areas. We first investigated whether individuals reduce predation risk by avoiding long-distance movements under windy conditions. We then analysed whether they favour moving upwind to maximise their information gain as they travel. We found no clear decrease in the largest step length as wind speed increases and suggest that local habitat could buffer the strength of wind speed (i.e. topography or vegetation). We, however, found that large herbivores tend to move upwind rather than cross- or downwind, although the effect was generally small. We point out that individuals might be more constrained in their use of cues carried by the wind than initially thought, due to the existence of dominant wind directions at all sites. Altogether, our study suggests that wind has little general, consistent, effects on large herbivore movement decisions. Some sites or species-specific results, however, call for delving deeper into the context-specificity of wind effects.