Dietary shifts: do grazers become browsers in the Thicket Biome?

Abstract

The diet of buffalo (Syncerus coffer) and Burchell's zebra (Equus burchelli) was investigated in the Addo Elephant National Park to test the hypothesis that the shortage of grass associated with thicket vegetation results in grazers increasing the proportion of dicotyledonous plant species in their diet. Diet composition, estimated from faecal analysis, indicated that 19 and 21 plant species were identified in the faeces of zebra and buffalo, respectively. Buffalo proved to have a higher percentage dicotyledonous (28.1 vs. 8.5 ) and lower percentage monocotyledonous (71.9 vs. 91.5 ) species in their diet than zebra. The grass Eragrostis curvula was found to be the dominant food item for both buffalo (18 of diet) and zebra (39 of diet) during the period of study. The present study indicated that a great proportion of the buffalo diet does in fact consist of grass, thereby refuting the perception that the Addo buffalo are primarily browsers. Both buffalo and zebra are specialised grazers and unsuited to a diet of browse. The probability of dietary shift by these grazers in the grass limited thicket vegetation is therefore challenged.