Brandt's cormorant (Phalacrocorax penicillatus), feeding on a bait ball of sardines, Los Islotes, La Paz, Baja, Mexico. Brandt's cormorants, also known as brown cormorants, penciled cormorants or Townsend's cormorants, are seabirds belonging to the family Phalacrocoracidae. Their principle food is live fish which is caught by diving from the surface and propelling underwater using their feet. Some species have been observed at depths of over 40 feet. Cormorant feathers do not have a waterproof oily layer. It is thought that this reduces drag and enables the bird to dive more quickly. After fishing the birds must go ashore to dry their wings. The formation of sardines into 'bait balls' is an instinctual behaviour when threatened.