wwh, I Googled "Serengeti Plain"+hippopotamus (without the + sign) and found the description below of the fauna in the Serengeti National Park. Hippos are there along with wildebeest--don't see tsuwm's bewildebeest listed there, but what the hey?

"FAUNA The park is best known for the now unrivalled herd sizes of 'plains game', which migrate between seasonal water supplies and grasslands. These include wildebeest Connochaetes taurinus (LR), zebra Equus burchelli, Thomson's gazelle Gazella thomsoni (LR), numerous prides of lion Panthera leo (VU) numbering up to 3,000 individuals (Packer, 1996), and spotted hyena Crocuta crocuta (LR). In May and June many game animals take part in a mass migration away from the central plains into the western corridor. The annual wildebeest migration is described in SRCS (1992) and Murray (1992). In the 1950s the wildebeest population is thought to have numbered 190,000, subsequently increasing to an estimated 1.69 million in 1989 (SRCS, 1992), and 1.27 million in 1991 (TWCM, 1992). Other characteristic mammals are leopard Panthera pardus, cheetah Acinonyx jubatus (VU), elephant Loxodonta africana (EN) estimated to number 1,357 in 1994 (Said et al., 1995), black rhinoceros Diceros bicornis (CR), hippopotamus Hippopotamus amphibius, giraffe Giraffa camelopardalis (LR), buffalo Syncerus caffer (LR), topi Damaliscus lunatus (LR), waterbuck Kobus ellipsiprymnus (LR), eland Taurotragus oryx, sitatunga Tragelaphus spekei (LR), bushbuck T. scriptus, oryx Oryx gazella (LR), reedbuck Redunca redunca (LR), mountain reedbuck R. fulvorufula (LR), numerous species of rodents and bats, golden jackal Canis aureus, side striped jackal C. adustus, Grant's gazelle Gazella granti (LR), seven species of mongoose, two species of otter, warthog Phacochoerus aethiopicus, and seven species of primate. Smaller predators include bat-eared fox Otocyon megalotis and ratel Mellivora capensis. The last packs of wild dog Lycaon pictus (EN) disappeared from the park in 1991. A rabies epidemic killed three of the packs, but there is no clear consensus on the full cause of the disappearance (Morell, 1995; Dye, 1996; East and Hofer, 1996)."

http://www.wcmc.org.uk/protected_areas/data/wh/serenget.html

Best regards,
WildeWord