The ecology of African buffalo (Syncerus caffer) in the Okavango Delta, Botswana
project overview
African buffalo (Syncerus caffer) form a large part of the total mammalian biomass of the Okavango Delta. Their large size, combined with their gregarious nature, means that herds several hundreds or even thousands strong are likely to have a substantial impact on their environment. The changeable terrain and high water levels found in the Okavango Delta make for challenging fieldwork conditions, which is why, prior to this study, very little research had been carried out on herbivore species in the ecosystem.
This project was set up to study the basic ecology of African buffalo in the Okavango Delta, with the following specific objectives:
This study constituted Emily Bennitt’s PhD project, and was completed between 2007 and 2012.
This project was set up to study the basic ecology of African buffalo in the Okavango Delta, with the following specific objectives:
- To identify the seasonal resource requirements of African buffalo
- To quantify seasonal changes in population demographics
- To determine which vegetation characteristics governed habitat and microhabitat selection
- To understand the social dynamics of the Delta population
- To compare behaviour and resources in migratory and resident sub-populations
This study constituted Emily Bennitt’s PhD project, and was completed between 2007 and 2012.
methods
Three seasons were defined based on changing water availability: rainy (December – March), early flood, when floodwaters were rising (April – July) and late flood, when floodwaters were receding (August – November). Fifteen buffalo cows in different herds were fitted with GPS-enabled satellite collars from Followit (Sweden). The collars were deployed for 3 – 16 months, after which they were removed or fell off. The collars were programmed to record one GPS fix per hour; these fixes were sent via satellite to a server every 10 hours, and were accessible in e-mail format shortly afterwards.
Data from the collars were used to cluster fixes into four behaviours: resting, grazing, walking and relocating. Sites where buffalo engaged in each of these activities were identified and assigned a habitat type based on a map developed from satellite images. These sites were visited within two weeks of use and vegetation characteristics were recorded. During these field trips, population demographics (age and gender) were recorded from all encountered buffalo herds.
Data from collared animals revealed two sub-populations: one resident and the other migratory, on the western side and eastern side of the study area, respectively. Comparisons were made between the vegetation characteristics available to those two sub-populations, and between spatial and behavioural patterns of the buffalo.
Data from the collars were used to cluster fixes into four behaviours: resting, grazing, walking and relocating. Sites where buffalo engaged in each of these activities were identified and assigned a habitat type based on a map developed from satellite images. These sites were visited within two weeks of use and vegetation characteristics were recorded. During these field trips, population demographics (age and gender) were recorded from all encountered buffalo herds.
Data from collared animals revealed two sub-populations: one resident and the other migratory, on the western side and eastern side of the study area, respectively. Comparisons were made between the vegetation characteristics available to those two sub-populations, and between spatial and behavioural patterns of the buffalo.
Findings and publications
In the Okavango Delta, African buffalo ecology was mainly driven by seasonal changes in forage and water availability. During the rainy season, seasonal pans were filled across the landscape and primary production increased in all habitats, allowing buffalo to shift their home ranges towards areas with the most productive habitats. During the flood seasons, water availability was restricted to floodplains and permanent channels, so buffalo home ranges were located close to those habitats. During the late flood season, waters receded from the floodplains, inducing new growth of floodplain grasses at a time when herbaceous material in other habitats was most senescent. Buffalo were reliant on floodplains during the late flood season, when these habitats provided resource buffers during the harshest time of year.
Buffalo gave birth throughout the year, but there was a peak during the rainy season. Adult males associated with breeding herds all year round, but this also peaked during the rainy season, when mating opportunities were at their highest. Buffalo herds in the delta were very fluid in comparison to records from other locations. There were approximately 3,000 and 5,000 animals in the resident and migratory sub-populations, respectively, which all shared the same home ranges but formed highly dynamic fission-fusion societies. No collared animals were consistently found in herds of the same size.
Buffalo behaviour varied with habitat: they rested more in riparian woodland than in open habitats, and grazed more in the latter. At the microhabitat scale, resting sites were most different from grazing and walking sites, but the distinguishing characteristics varied with habitat type.
Publications:
Bennitt E. 2012. The ecology of African buffalo (Syncerus caffer) in the Okavango Delta, Botswana. [PhD thesis]. Bristol (UK): University of Bristol. (pdf)
Bennitt E, Bonyongo MC, Harris S. 2014. Habitat selection by African buffalo (Syncerus caffer) in response to landscape-level fluctuations in water availability on two temporal scales. PLoS ONE. 9(7):e101346. (pdf )
Buffalo gave birth throughout the year, but there was a peak during the rainy season. Adult males associated with breeding herds all year round, but this also peaked during the rainy season, when mating opportunities were at their highest. Buffalo herds in the delta were very fluid in comparison to records from other locations. There were approximately 3,000 and 5,000 animals in the resident and migratory sub-populations, respectively, which all shared the same home ranges but formed highly dynamic fission-fusion societies. No collared animals were consistently found in herds of the same size.
Buffalo behaviour varied with habitat: they rested more in riparian woodland than in open habitats, and grazed more in the latter. At the microhabitat scale, resting sites were most different from grazing and walking sites, but the distinguishing characteristics varied with habitat type.
Publications:
Bennitt E. 2012. The ecology of African buffalo (Syncerus caffer) in the Okavango Delta, Botswana. [PhD thesis]. Bristol (UK): University of Bristol. (pdf)
Bennitt E, Bonyongo MC, Harris S. 2014. Habitat selection by African buffalo (Syncerus caffer) in response to landscape-level fluctuations in water availability on two temporal scales. PLoS ONE. 9(7):e101346. (pdf )