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.
♦ ²An estimate of summer food consumption of six seabird species in Iceland, K. Lilliendahl and J. Solmundsson, ICES Journal of Marine Science, 54: 624–630. 1997