Additional Data and Perspectives on Interspecific Aggression in the Common Loon, Gavia immer

Abstract

We witnessed the killing of a female Redhead (Aythya Americana) by a male Common Loon (Gavia immer). The wound was delivered into the abdomen from below, and death occurred because of a torn, hemorrhaging liver. This same Common Loon also threatened a female Ring-necked Duck (Aythya collaris) with ducklings. We hypothesize that interspecific aggression by loons might be energetically costly but is sometimes adaptive because it deters predators.