Seasonal Resource Fluctuations Determining Movement Patterns and Group Dynamics of Semi-Arid Herbivore Populations

Abstract

The semi-arid ecosystem is known to have very unpredictable spatial and temporal fluctuations in water availability and primary production, thus compelling native herbivores and those raised domestically to constantly modify their behavior. This paper aims to demonstrate how the changes in the availability of resources over the seasons define the movement monitoring, habitat selection, and social dynamics of herds. By applying the technique of combining remote sensing indexes of plant growth, satellite global positioning systems, and direct observation of groups, we studied changes in the behavioral patterns between wet and dry seasons. The outcome of our study showed that the seasonal tactics used were deliberate, as the wet season provided more food for herbivores to form large fission-fusion groups traveling fast over extensive areas; however, the dry season led to clustering within small areas near water sources and resource-driven group formation. The statistics confirmed that primary vegetative mass and distance to the source of water accounted for more than seventy-five percent of the variation in herd migration steps and size. Moreover, population-level modeling showed that increased rain fluctuations are a risk for traditional migration routes and waterhole disease transmission. Overall, the above observations prove that semi-arid large herbivores have a flexible, non-linear behavior in response to weather extremes, which is crucial from an ecological perspective to develop any adaptive management framework of rangelands, safeguard movement routes, and sustain pastoral livestock production systems amid ongoing climate disruptions.