The distribution of cattle and their interaction with the African Buffalo at the wildlife-livestock interface understood using real-time Global Positioning Systems (GPS) and remotely sensed data

Abstract

The distribution of herbivores is hypothesized to be influenced by an interplay of several biophysical factors as well as human factors. However, our current understanding of herbivore movement dynamics and factors driving the movement and interaction between domestic and wild herbivores at interfaces between wildlife and livestock areas is limited. In this regard, the development of methods and approaches that allow spatially explicit (1) continuous monitoring, and (2) prediction of animal movements in relation to biophysical and human factors is critical for an improved understanding of livestock and wildlife distribution at these interfaces. The advent of Global Positioning Systems (GPS), remote sensing and improved spatial analytical frameworks has provided opportunities to accomplish this task. In this thesis, we develop novel methods and approaches using GPS and remote sensing to understand factors influencing the distribution of livestock, i.e. cattle (Bos taurus) and their spatial overlap with wild herbivores i.e. the African buffalo (Syncerus caffer) at a wildlife-livestock interface. Results showed that the distribution of GPS collared cattle was closely linked with the spatial variation of remotely sensed foliar nitrogen signifying for the first time that new advanced multispectral sensors, particularly WorldView-2 could be used for predicting and mapping forage quality. Results also showed that cattle are central place foragers as distance from the kraal influenced habitat selection. This is the first time that the central place effect has been included in habitat selection models for large herbivores. In this thesis results showed that habitat composition explained shifts in space use as both the home range and core areas shifted in response to variations in habitat composition. Results showed that herbivores responded differently to the effects of landscape structure and landscape productivity depending on season (wet or dry). In fact, only landscape structure explained wet season cattle distribution while both landscape structure and landscape productivity influenced dry season distribution. For the first time in thesis, we showed that intensity of spatial overlap between cattle, a non-territorial species, conformed to that predicted for territorial species where overlap is high at both low and high levels of food abundance whilst low at intermediate levels. This indicates that the influence of food on intraspecific overlaps is species-independent, thus, allowing for wider applicability of the model. Moreover, results showed that using GPS-derived movement metrics, deviations in animal behaviour and movement could be modeled as a function of herder presence. This finding opens unprecedented possibilities for monitoring deviations in animal behaviour using GPS. We demonstrated that resource (vegetation greenness) gradients exist at wildlife-livestock interfaces and that these gradients drive livestock movement into conservation areas resulting in overlaps with the African buffalo. We also found that during resource limited periods both spatial aggregation and segregation occurred between cattle and buffalo, indicating potential resource competition. Overall, in this thesis we have demonstrated the potential of combining GPS data, remote sensing and spatial analysis in advancing our understanding of movement dynamics and factors influencing the distribution of livestock and their spatial overlap with wildlife at a wildlife-livestock interface.