Facilitation between bovids and equids on an African savanna

Background: Equids, especially zebras and donkeys, and cattle (bovids) share habitats in many savanna ecosystems in Africa. The issue of competition for food between these ungulate guilds remains largely unresolved. Resolving it will provide insights into how wild zebra are likely to interact with cattle on shared landscapes and suggest best practices for cattle owners who must decide whether to tolerate wild ungulates, some of which are severely threatened (e.g. Grevy’s zebra, Equus grevyi). Aim: Determine whether an equid and a bovid compete in a semi-arid savanna in Kenya. Organisms: Boran cattle (Bos indicus) and donkeys (Equus africanus asinus) – the latter as surrogates for zebras. Methodology: Experiments to measure performance (weight gains), bite rates, diet quality (digestible organic matter and crude protein), and gastrointestinal worm burdens (parasite egg count per unit weight of faeces) of the two ungulate species when herded separately (single species) or together (mixed species). We used two stocking levels: low-density (one animal per 7 ha), a level typical of commercial ranchers; and high-density (one animal per 2 ha), a level typical of pastoral herders. Principal findings: When herded together, both species gained more weight, had higher bite rates (especially at low stocking density), and selected diets with a more favourable balance between digestible organic matter and crude protein, than when herded separately. In addition, parasite egg output in faeces of donkeys was reduced by 14–35% following shared foraging with cattle. Conclusion: Cattle (a ruminant) and donkeys (hindgut fermenters, closely related to zebras) showed no evidence of competion with each other. Rather, our results show a facilitative, rather than a competitive, interaction between them

Relationships Between Cattle and Biodiversity in Multiuse Landscape Revealed by Kenya Long-Term Exclosure Experiment

On rangelands worldwide, cattle interact with many forms of biodiversity, most obviously with vegetation and other large herbivores. Since 1995, we have been manipulating the presence of cattle, mesoherbivores, and megaherbivores (elephants and giraffes) in a series of eighteen 4-ha (10-acre) plots at the Kenya Long-term Exclosure Experiment. We recently (2013) crossed these treatments with small-scale controlled burns. These replicated experimental treatments simulate different land management practices. We seek to disentangle the complex relationships between livestock and biodiversity in a biome where worldwide, uneasy coexistence is the norm. Here, we synthesize more than 20 yr of data to address three central questions about the potentially unique role of cattle in savanna ecology: 1) To what extent do cattle and wild herbivores compete with or facilitate each other? 2) Are the effects of cattle on vegetation similar to those of wildlife, or do cattle have unique effects? 3) What effects do cattle and commercial cattle management have on other savanna organisms? We found that 1) Cattle compete at least as strongly with browsers as grazers, and wildlife compete with cattle, although these negative effects are mitigated by cryptic herbivores (rodents), rainfall, fire, and elephants. 2) Cattle effects on herbaceous vegetation (composition, productivity) are similar to those of the rich mixture of ungulates they replace, differing mainly due to the greater densities of cattle. In contrast, cattle, wild mesoherbivores, and megaherbivores have strongly guild-specific effects on woody vegetation. 3) Both cattle and wild ungulates regulate cascades to other consumers, notably termites, rodents, and disease vectors (ticks and fleas) and pathogens. Overall, cattle management, at moderate stocking densities, can be compatible with the maintenance of considerable native biodiversity, although reducing livestock to these densities in African rangelands is a major challenge.The Rangeland Ecology & Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information