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.
♦ ²Diet of Harp Seals (Phoca groenlandica) in Divisions 2J and 3KL During 1991–93, J. W. Lawson, G. B. Stenson and D. G. McKinnon, NAFO Sci. Coun. Studies, 21: 143–154 (1994)