Its distinctive black-and-white plumage gives the Common Loon great visual appeal, but the Common Loon’s haunting calls add another dimension to its popularity. Common Loons produce four major call types: wails, yodels, tremolos, and hoots.
Wails are howl-like calls that resemble the notes of a clarinet and can travel great distances across calm water. Wails serve to keep loons in contact with one another, and are often the first calls in Common Loon choruses. At night, a series of several wails may be followed by a succession of yodels, tremolos, or tremolo duets as loons from miles around begin vocalizing in chorus. Some observers have likened the wail to dialing a “1” when placing a long-distance phone call; once acoustic contact is achieved, several loons get in on the “conversation.”
Yodels are the most complex calls in the Common Loon’s repertoire. They are produced only by males and are an important component of a male loon’s ability to defend his territory. Each male loon can be identified by a unique vocal signature encoded in his yodel. The crouching posture associated with the yodel, as depicted in the photo, probably helps increase the distance over which the sound travels, warning distant rivals to stay away.
Tremolos are sometimes referred to as the “laugh” of the loon, and their trembling quality is probably the source of the expression “crazy as a loon.” Tremolos are sometimes associated with situations in which a loon may feel threatened or is defending its chicks from a perceived threat. Other times, the male and female of a pair may tremolo in duet, a cooperative display that may reinforce the pair bond or announce the presence of the bonded pair to neighbors or rivals.
Hoots are intimate calls that occur between members of a pair or a parent loon and its chicks. Occasionally, hoots precede certain visual displays (e.g., splash-dives) or occur during social interactions with territory intruders.