Changing territories, changing tunes: male loons, Gavia immer, change their vocalizations when they change territories

Male common loons produce a territorial vocalization called the yodel. Each male loon has a characteristic yodel that is stable from year to year and differs from that of other male loons on other lakes. Of 13 male loons whose yodels we recorded before and after they changed territories, 12 substantially changed their yodels either the first or second year on the new territory. Furthermore, this change increased the difference between the new resident's yodel and that of the previous resident. This result implies that loons not only change their vocalizations as the birds change territory, but also that the new owner is familiar with the yodel of the resident that it replaces.