 Reference Base  The mammals of the southern African subregion, new edition |
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| Location: |
World |
| Subject: |
Ecology - Food |
| Species: |
White Rhino |
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White rhinoceros are grazers with a preference for feeding on short grass, which they are capable of cropping to within 25-60 mm of the ground (Owen-Smith, 1988). Lacking incisor teeth, the movable and extremely sensitive upper lip is extended over a grass clump, pressing the grass against the hard lower lip to be cropped with an upward movement of both lips. Sometimes the process is assisted by a slight movement of the head. As the individual feeds the head is held low, the wide nostrils maintaining contact with the grass.
They are selective feeders. Owen-Smith (1973) gave the bite width of an adult female as about 200 mm and estimated that about 48% of daylight hours are taken up in feeding. Feeding rate on short grass averaged 78 bites per minute. In doing so they stand in one place, moving the head in an arc, then take a step forward to repeat the process. in wetter years when the grass is taller they do not crop the grass as short, and their bite rate is greatly reduced (Emslie, pers. comm.) They may chew the food for a moment or two, but do not ruminate.
Owen-Smith (1973) showed that, in Natal, four species of grasses constituted 74% of the food intake, these being: red grass, Themeda triandra (an important dry season food resource); buffalo grass, Panicum maximum; small buffalo grass, P. coloratum, and common signal grass, Urochloa mosambicensis, the first-named being by far the most heavily utilised, sprouting green grass being preferred. In a study of wet season feeding behaviour of grazers in west Umfolozi in 1984, Emslie (pers. comm.) found that 42% of the grass biomass in white rhinoceros feeding patches was made up of Urochlou mosambicensis and Panicum maximum. Both these species favour lower-lying, more alluvial soils. P. maximum is also a species often found in shady sites under trees. These two species contributed 51% to the diet. Themedo triandra, Sporobolus smutsii and Panicum coloratum contributed a further 33% to the diet. White rhinoceros were found to preferentially graze the shorter, more erect central tillers of P. coloratum than the longer, more prostrate side stoloniferous tillers (Emslie, 1985; Diamond, 1986). Some 30 other species. are eaten to a lesser extent. Other species such as the resinous turpentine grass, Gymbopogon plurinodis, are rigorously avoided.
Owen-Smith (1973) recorded geophagia, especially around termitaria.
White rhinoceros drink water regularly and are dependent on its availability. Owen-Smith (1973) found that most drinking is done between 17h00 and 21hoo and continues after sundown, less drinking taking place during the day. A drinking frequency of every 2-3 days was most usual during the dry season.
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