Tracing the Source of the Elephant And Hippopotamus Ivory from ...

differences in the frequency of species. Another culling study by van Hoven (1983) in
Kruger National Park (South Africa) concluded that hippos largely ate grass in proportion
to the availability of the grass, which according to the author agrees with an earlier study
in Kruger National Park conducted by Young (1966). Field’s studies, nevertheless, are
more likely accurate, and thus his conclusions more likely correct, since van Hoven only
identified plant species and not their percentages. However, only differentiating between
browse and graze is necessary for the purposes of this research, and the hippo is
decidedly a grazer, overwhelmingly consuming grasses, some of which are likely to be
C4 grasses.
Even so, hippos are known to consume other types of food, particularly in times
of environmental stress such as drought or high grazing animal density, which would
limit the availability of grass. These other types of food include elephant dung (Dudley
1996: 488; Dudley 1998: 58), fruit (i.e. Acacia albida. Eltringham 1999: 79; Dunham
1990), aquatic plants (van Hoven 1983: 48; Field 1970; Mugangu and Hunter 1992;
Eltringham 1999: 79), and even other animals (Dudley 1996: 486-487, 1998: 58-59;
Eltringham 1999: 82-84).
While it is generally agreed that aquatic plants are not a significant part of the
hippo’s diet, small amounts are consumed. Young (1966) in his Kruger NP study found
traces of reeds (Phragmites communis) in the stomachs of the hippos (as reported by van
Hoven 1983: 48). Eltringham (1993, 1999) also reports from Field’s research (1970) that
hippos were seen eating a floating plant, the Nile cabbage (Pistia stratiotes), and having
witnessed the same behavior himself, Eltringham is of the opinion that the hippos
“appeared to be merely toying with the plants in a rather bored, desultory way and it is
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