Attributes / relations provided by
♦ ¹del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona.
♦ ²C. R. Field (1970) A Study of the Feeding Habits of the Hippopotamus (Hippopotamus amphibius Linn.) in the Queen Elizabeth National Park, Uganda, With Some Management Implications, Zoologica Africana, 5:1, 71-86,