Attributes / relations provided by
♦ ¹Food of Northwest Atlantic Fishes and Two Common Species of Squid, Ray E. Bowman, Charles E. Stillwell, William L. Michaels, and Marvin D. Grosslein, NOAA Technical Memorandum NMFS-NE-155 (2000)
♦ ²del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona.