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.
♦ 2Nestling diet and parental provisioning behaviour in the Marsh harrier (Circus aeruginosus), Marcin BRZEZIŃSKI, Michał ŻMIHORSKI, Acta Zoologica Lituanica, 2009, Volumen 19, Numerus 2