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 harbour seal Phoca vitulina as a predator in the Skagerrak. Haerkoenen, T | Heide-Joergensen, M-P, Ophelia. Vol. 34, no. 3, pp. 191-207 1991