Loon (Gavia immer) Science Article 1
Breeding Common Loons (Guvia immer) are well known for vigorously defending their territory from conspecifics. Territory holders are not previously known to be supplanted by loons during the breeding season. I observed a pair of adult Common Loons displace a resident pair from their territory shortly after a territorial conflict; the takeover coincided with the death of the resident loons’ chick caused by an adult Bald Eagle (Hali etus leucocephalus).
James D. Paruki, Wilson Bull., 111(l), 1999, pp. 116-117