Common hippopotamuses (hippos), Hippopotamus amphibius, yawning, Kruger National Park, South Africa, Africa

Common hippopotamus (Hippopotamus amphibius), Kruger National Park, South Africa, Africa

Common hippos, Hippopotamus amphibius, two young males sparring, Kruger National Park, South Africa, Africa

An adult hippopotamus (Hippopotamus amphibius) with a common moorhen, Ngorongoro Crater, Tanzania, East Africa, Africa

Hippo (Hippopotamus amphibius) opens mouth in foamy river water, Grumeti Serengeti Tented Camp, Serengeti National Park; Tanzania

Hippopotamus (Hippopotamus amphibius) turns towards camera on river bank, Serengeti, Tanzania

Common hippopotamus (Hippopotamus amphibius) walks among others in shallows in sunshine in Serengeti National Park, Tanzania

Common hippopotamus (Hippopotamus amphibius) walking in shallows in sunshine in Serengeti National Park, Tanzania

Common hippopotamus (Hippopotamus amphibius) roars at another in river in Serengeti National Park, Tanzania

Hippo (Hippopotamus amphibius) stands in long grass facing camera, Grumeti Serengeti Tented Camp, Serengeti National Park; Tanzania

Close-up of two hippo (Hippopotamus amphibius) fighting and splashing in water, Serengeti, Tanzania

Hippo (Hippopotamus amphibius) stands in water staring at camera, Grumeti Serengeti Tented Camp, Serengeti National Park; Tanzania

Hippopotamus (Hippopotamus amphibius) on river bank bends to drink, Serengeti, Tanzania

Hippopotamus (Hippopotamus amphibius) coming up out of the water, Botswana

A backlit male hippopotamus (Hippopotamus amphibius) stands half-submerged in water, staring menacingly towards the camera. His skin is pink and grey, and one ear is folded back. Grumeti Serengeti Tented Camp, Serengeti National Park; Tanzania

Hippo (Hippopotamus amphibius) grazes in long grass eyeing camera, Grumeti Serengeti Tented Camp, Serengeti National Park; Tanzania

Common Hippo (Hippopotamus amphibius) in the water, Masai Mara National Reserve, National Park, Kenya

Common Hippo (Hippopotamus amphibius) in the grass, Masai Mara National Reserve, National Park, Kenya

Common Hippo (Hippopotamus amphibius), showdown, South Luangwa natioinal Park, Luangwa river, Zambia

Common Hippo (Hippopotamus amphibius), Luangwa river, South Luangwa national Park, Zambia

Common Hippo (Hippopotamus amphibius) in the water, Masai Mara National Reserve, National Park, Kenya

Common Hippo (Hippopotamus amphibius), Zambezi river, Lower Zambezi national Park, Zambia

Common Hippo (Hippopotamus amphibius), injured during a fight with an another male, Luangwa river, South Luangwa natioinal Park, Zambia

Common Hippo (Hippopotamus amphibius), outside the water, South Luangwa natioinal Park, Luangwa river, Zambia

Common hippopotamus (Hippopotamus amphibius). Eastern Shores. Isimangaliso Wetland Park. KwaZulu Natal. South Africa