Grazer movements: spatial and temporal responses to burning in a tall-grass African savanna

Abstract

The consequences of burning on grazer distributions in the landscape were investigated in a savanna system in South Africa. Distribution and extent of fires can be highly variable within and between years, but how this influences patterns of grazing is not well understood. Three years of fire and grazer distribution data from Hluhluwe-Umfolozi Park, KwaZulu Natal were used to describe how animals respond to different burn situations. Animals were attracted to the burnt areas after fires and this resulted in a decrease in grazer densities in unburnt areas. This effect was more pronounced when a larger area of the park had burnt, and increased over time as area burnt increased. Thus, grazing pressure in an area will depend on the size, timing and distribution of fires in a larger spatial context. Fires also seem to promote a more uniform grazing environment: although grazer density overall is higher in areas that have burnt, the grazers are more dispersed in these areas, and grazing at any one point may be less intense than in the unburnt areas (which are grazed patchily). Therefore at the beginning of the wet season—a key time of year for grass growth—fires are acting to decrease grazing pressure at any one point in both burnt and unburnt areas. The presence of fire in grazing systems could affect grass community composition because fire alters the intensity and frequency of utilisation of the grass sward.