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.
♦ ²The Diet of the Hippopotamus in Ndumu Game Reserve, Natal, as Determined by Faecal Analysis, J.S.B. Scotcher, D.R.M. Stewart, C.M. Breen, S.-Afr. Tydskr. Natuurnavors. 8:1-11 (1978)