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 PREDATION OF GUANO BIRDS ON THE PERUVIAN ANCHOVY (Engraulis ringens JENYNS), Romulo Jordán, CALIFORNIA COOPERATIVE OCEANIC FISHERIES INVESTIGATIONS, REPORTS VOLUME XI, 1 JULY 1963 TO 30 JUNE 1966, p. 105-109