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.
♦ ²Seasonal and geographical variations in the diet of Common Guillemots Uria aalge off western Scotland, D J Halley, N. Harrison, A. Webb and D.R. Thompson, SEABIRD 17: 12-20