Hoot: A soft short contact call between birds. Adults will hoot to each other, and parents will hoot to chicks, enabling them to keep in touch with the other birds.
Wail: A long, one, two, or three note call used in situations when loons want to move closer to one another. Parents wail to their chicks to encourage the chicks to leave the nest, approach the parents when they have food, or emerge from a hiding place. Listen to a wail.
Tremolo: Often called the "laughing call" of the loon, the tremolo is actually an alarm call used in threatening situations, such as when a boat is approaching a chick or a nest too closely. This call is also the “flight call”, and is often heard when a loon is flying overhead, particularly if it is going over a lake with other loons on the water. It is also used in the "nocturnal chorus." Members of a pair will “duet” using tremolo calls mixed with wails.
Yodel: This call is produced exclusively by males, and is used in territorial situations and aggressive encounters with other birds. Males will also yodel if a predator is seen that may be approaching the chicks, such as when an eagle flies overhead. Yodeling males crouch flat to the water with their head and neck extended and the lower bill just over the water.
Chick begging call: When hungry, a chick will peep and peck persistently at the parent's bill, encouraging the parent to hunt for food for the chick.
Chick distress call: Chicks call out almost continuously with peeps, yelps, and wails when they are separated from their parents. The adult birds respond by moving closer to the chicks, and may hoot or wail to contact the chick.
Loon calls courtesy of Dr. Jay Mager.