EFFECTS OF LIVESTOCK ON WILDLIFE ON SHARED RANGELANDS

Abstract

ABSTRACT

Livestock graze more than a quarter of earth’s land surface. This is generally considered detrimental to wildlife, but grazing can sometimes have positive effects as well. Rangelands also provide vital habitat for wildlife outside of protected areas. Consequently, conservation efforts are increasingly aimed at managing land for wildlife-livestock coexistence. However, much is still unknown about how wildlife respond to livestock grazing.

Chapter 1 is a systematic review of the literature examining evidence for positive and negative effects of livestock grazing on wildlife around the world. A number of big patterns emerge, but also significant gaps in current data. Most studies have been conducted in North America and Europe on birds and mammals, and there is a strong need for more research in the developing world, on a wider range of species. In the following chapters, my work on cattle and wild ungulates in Africa attempts to address some of those gaps.

Chapters 2 and 3 are methods papers that provide the foundation for the field studies discussed in chapters 4 and 5. In Chapter 2, I developed a method for using low-cost GPS loggers to track cattle movements, quantify variation in intensity across a study area, and assess the impact of cattle on vegetation. This tracking can provide important insights and guide management decisions. Chapter 3 describes a method for analyzing camera trap data to quantify wildlife use of a site, especially for social animals like ungulates that often live in groups of varying sizes.

Chapters 4 and 5 present results on effects of cattle grazing on rangelands in an integrated livestock-wildlife system in Kenya. Chapter 4 analyzes the effects of cattle movements and grazing intensity on forage quantity and quality. While grazing does remove grass biomass, it can also stimulate new growth and “green-up” after rain leading to improved grass quality. Chapter 5 then discusses the responses of a suite of wild grazers to cattle grazing. Grazing may benefit small species, especially ruminants, whereas large buffalo require tall grass. As non-ruminants, zebras are able to utilize a wide range of habitats but may benefit from cattle-induced grass green-up.