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.
♦ ²Birds and berries: a study of an ecological interaction. Calton, Great Britain, Snow B.K., Snow D.W., 1988, T & AD Poyser. 268 p.