Diets of sympatric hippopotamus (Hippopotamus amphibius) and zebus (Bos indicus) during the dry season in the "W" National Park (Niger Republic).
In West Africa, about 7,600 hippopotamuses, Hippopotamus amphibius, are scattered in small groups over a wide area shared by 18 countries. The group that inhabits the "W" National Park is undoubtedly one of the most endangered because of its small size. During the dry season from January to March 2004, we conducted both faecal and grazing analyses to characterise suitable habitats for the hippos, taking into account the potential competition with cattle. Comparisons of diets between hippo and zebu, Bos indicus, show that the hippos are the most selective since they forage on only six plant species (mainly grasses), while the diversity of plants eaten by zebus is wider (17 species). The co-existence of these two herbivores in the islands of the Niger River, which forms the northern boundary of the park, may lead to the decline of the hippo population if the habitats are not conveniently shared between them. The management of zebu/hippo competition should particularly take the respective abundances of the preferred plant species into account. These are: Commelina nudiflora, Echinochloa colona and Oryza brachyantha for the hippo, and Echinochloa pyramidalis and Indigofera astragalina for the zebu.