Ecology of Buffalo in the Okavango

The project aims to increase understanding of the ecology of the African buffalo in the Okavango Delta so that a conservation and management plan for the species can be developed.

Very little information is available on the behaviour and ecology of the buffalo in this specific region, yet they are likely to play a key role within the ecosystem. Defining this role will help to predict the impact of any potential changes to the delta, not only on the buffalo themselves, but also on the habitats that they use and on the sympatric herbivores that may benefit from their presence.

Background

The Okavango Delta is a unique ecosystem that supports a high diversity of wildlife, including many herbivorous species. The African buffalo (Syncerus caffer) is one of the largest herbivores present in the Okavango Delta, with males weighing up to 700 kg and females weighing up to 500 kg. Herbivorous species with a large body mass are more tolerant of low quality foods than those with a smaller body mass, and are consequently able to forage in a wider range of habitats.

However, the region is under threat, especially from water loss and the encroachment of human activity on its boundaries. There are plans to build dams in Angola and Namibia, where the water from the Okavango River would be diverted to towns and used for irrigation. This would diminish the amount of water flowing into the Delta system, causing a reduction in the area of floodplains and all the wildlife that they support.

The buffalo's ability to consume low quality vegetation, together with the trampling effect that would ensue from a large herd of buffalo passing through a habitat, could provide a basis for the facilitation of other species of herbivore. The feeding habits of the buffalo may remove the taller grasses, as well as those of lower nutritional value, thus 'opening' the habitat for smaller herbivores by increasing access to shorter, higher quality forage. This phenomenon which has been observed in the Ngorongoro Crater has buffalo and zebra entering the drying grasslands before wildebeest and gazelles, which follow once the taller grasses have been grazed and trampled to a more convenient height.

Project details

The first step in determining whether this type of interaction is taking place is to identify the ways in which buffalo modify the habitats that they use.

African buffalo have been studied in a few other sites across Africa; however information with regards to the buffalo population of the Okavango Delta is sparse. Based on previous observations, one would expect the buffalo to consume a reasonably wide range of grass species, concentrating on the most nutritionally viable ones whenever possible. However, when those species with high nutritional value become less abundant, for example during the dry season, buffalo tend to reduce their selectivity and consume higher quantities of lower quality plants to compensate.

Using various methods, including fitting nine individuals with GPS collars and observational information, the project will gather information on population demographics, home ranges, diet, and habitat modification.

Aims and objectives:
1. To monitor the demographics of a population of buffalo, including age and sex ratios, recruitment rates and body condition scores, in order to identify any trends and apply these to the entire population of the Okavango Delta.
2. To map the monthly and seasonal home ranges of the study population, including any habitat preferences, and identify causes for these preferences.
3. To determine the foraging patterns of the population in terms of the plant species consumed and the factors influencing their choice of forage species.
4. To quantify effects that the feeding patterns shown by the buffalo may have on the quality and composition of the vegetation species in each habitat type, and to determine whether these effects could provide the basis for a facilitation interaction with sympatric herbivorous species.
5. To investigate the problems with the buffalo cordon fence (details below), as seen by the local farmers, and to suggest feasible solutions for those problems.

Increasing our understanding of the ecology of the Okavango Delta can only help to conserve this unique and fragile ecosystem so that it can be enjoyed for many more years to come.

Buffalo cordon fence

The study will also investigate the relationship between buffalo and the buffalo cordon fence that surrounds much of the Okavango Delta, which prevents the interaction between wildlife and domestic animals. Buffalo are carriers of numerous diseases that are also transmissible to cattle, such as foot and mouth disease and bovine tuberculosis. They graze similar areas and could present themselves as competitors for the forage available to cattle. The maintenance of the cordon fences themselves is apparently not satisfactory, with the result that elephants could damage them, allowing wildlife and cattle to mingle. This would cause problems with cattle depredation and the destruction of property by wildlife.

The GPS data obtained from the collared cows will be used to establish whether the herds approach the cordon fence. Areas where this is the case will be investigated to uncover any distinguishing features, such as weak points at the fence, or water or shade, which farmers may have provided for cattle. The species and nutritional quality of the vegetation found in such areas, together with the availability of such resources as water and shade, will be compared to those of their preferred habitats away from the cordon fence. This will also be useful in determining how buffalo would react to an increased human presence in the areas surrounding the Delta.

The farmers will be interviewed, with the help of a local to translate if necessary, to record their grievances with the fence, and what they suggest could be done to solve the problems. The farmers will be asked how they currently deal with any problems, whilst being aware that some measures may not be in accordance with protection laws. Stretches of the cordon fence will be examined at random to determine the average level of maintenance. This maintenance should be kept highest in areas where farmland and villages are located in close proximity to the fence.