Individual Loon Behaviors

Comfort Movements--Behaviors that improve the loon’s comfort

Comfort movements include stretching muscles as with a wing stretch or a foot waggle. During a wing stretch the loon rises out of the water and stretches both wings back and flaps them. A foot waggle is when a loon stretches a foot out of the water and shakes it.

Sometimes loons show their greatest acrobatic talents while bathing. They will flip, dive aggressively, smack the water hard with their wings, and essentially look like a loon that’s possessed. They likely do this to force water through their feathers to extract dirt and feather parasites.

Loons are diving birds and thus must take meticulous care of their feathers to maintain their water repellency. Loons spend much of their life on the ocean and in cold water lakes. Their waterproof feathers prevent the water from reaching their skin and causing hypothermia. The waterproof outer feathers produces an insulating layer of air between them and the skin to further help keep the loon warm in cold water. Preening behaviors involve extracting oil from the uropygial gland near the base of the tail and working the oil through all of the feathers. To reach their belly and side feathers, loons will roll to one side. They will rub their heads on their backs to waterproof head feathers.

Feeding

Loon Hunting for Food Photo courtesy of Harold Dziuk

Loons hunt for fish and crustaceans under water. They will sometimes begin a foraging excursion by lowering their head into the water and “peering” for their prey. When a prey item is spotted, they will dive and swim after their quarry. Loons are skillful and agile swimmers and use their large webbed feet for propulsion. They hold their wings close to their bodies. When they catch their quarry, they come back to the surface. A loon may spend 5-10 minutes trying to orient its prey so it can be swallowed head first.  

Interactions between Loons

Courtship

Mated pairs spend much of their time together especially early in the breeding season. They are often seen swimming side-by-side and making short dives together. Sometimes as they swim together they will turn their heads away from each other and exhibit bill-dipping, signs of non-aggression.

Aggressive Encounters

Aggressive encounters seem to usually involve attempted territorial take-over of a breeding area or a feeding area. Early in the season, a male or a female will invade a territory and test the pair bond of the resident pair. If the intruder is a male, it will face-off with the resident male. If the intruder is a female, it will face-off with the resident female. Occasionally a pair will intrude and the four will face-off together; this is especially common on large lakes with adjacent territories. Later in the breeding season, a single adult or pair will face-off with any intruding loon in defense of its young. Even lone non-breeding loons occasionally have aggressive encounters over popular feeding areas. This type of encounter is usually resolved quickly with the “loser” moving on.

The loon’s primary weapon is its bill. Therefore most aggressive postures and movements involve threatening the opponent with the bill. A typical aggressive encounter sequence involves the loons coming together in the middle of the lake. They will circle swim, peer underwater, and jerk their heads. They will pint their bills directly at their opponent(s). All birds involved will occasionally jerk or splash dive. While underwater the loons attempt to stab their opponent with their bills.

The outcome of most encounters involves the expulsion of the losing loon (often the intruder) from the territory. The losing loon will either dive and swim out of the territory or fly off the lake. On rare occasions, loons may be injured or killed in aggressive encounters and will not be able to leave the lake. When injured, they often crawl on shore to avoid drowning or to evade the attacking loon.

Around the Nest

As a loon pair begins thinking about nesting, they will scout the shoreline of their lake for suitable places to nest. Once the nest site has been selected the pair will build the nest using mud, leaves, grasses, or any material surrounding the nest site or on the lake bottom. They will copulate on the nest and soon the female will lay 1-2 (rarely 3) eggs. The adults will take turns incubating the eggs and nest exchanges are usually followed by egg turning prior to settling onto the eggs. The eggs can withstand being exposed for extended periods of time when the weather is dry and warm.

Disturbance Near the Nest

Nesting Loon in Alerted Position Photo courtesy of Ralph LaPlant

If you (or potential predators) approach a loon nest, the behavior of the incubating loon will tell you if you are too close.  First, the loon may raise its head in an alerted position to better view the disturbance.

If you continue to approach, the loon will put its head down to the water and flatten its body in a hang-over posture to try to hide from view.  This indicates that you are too close!  If the loon perceives that danger continues to approach, it will slip off the nest and into the water. If the loon is startled, it will flush abruptly and may kick the eggs out of the nest.

A loon that is in the water and near the nest will often remain low in the water with only the head and sometimes part of the back above the water’s surface.It is trying to look small and out of view while it keeps on an eye on your activities near the nest.

If you approach the nest to closely, a loon in the water may penguin dance and try to lead you away from the nest. This is their most extreme reaction to human presence and means you are much too close to the nest (or chicks later on). This is not the time for taking pictures; you should leave the area immediately.

Chick Rearing

Loon chick backriding on adult Photo courtesy of Ralph LaPlant

As soon as a chick dries out after hatching, it is ready for the water. It can swim and make shallow dives even at this young age. It can be weary work keeping up with the adults; therefore young chicks are often seen backriding. This also serves to keep the chick warm and protected from flying and underwater predators. An adult will also wing tuck a chick which serves these same purposes.

Chicks are semi-precocial meaning they can leave the nest immediately and swim on their own. However, they are dependent on the adults to be fed until they learn to hunt on their own. Both adults will feed the chicks.

Fall Flocking and Migration

Early fall loon gathering Photo courtesy of Matt Dooley.

Towards the end of the breeding season, loons will begin to gather in small groups. Loons that did not breed or that were unsuccessful in hatching or rearing chicks likely group together first. By October, large flocks of 50 or more loons can be observed particularly on large lakes. Loons will migrate singly or in loose groups but don’t travel in tight flocks as do other birds. Adult loons will migrate earlier than the chicks. For the chicks, it is a race against time. They must grow strong enough to leave their natal lake before the winter ice forms.

As a migratory bird, loons are protected by the Migratory Bird Act which prohibits the harassment or killing of loons, eggs, or chicks. It is also illegal to possess loon feathers, eggs, nests, or entire birds. Midwestern loons spend the summer on northern inland lakes and head south or east in the fall to spend the winter on the Atlantic coast or in the Gulf of Mexico. Western common loons overwinter on the Pacific coast from Alaska to the Baja peninsula and in the Gulf of California.

Visit the USGS Common Loon Migration Study website to view the migration paths of Midwestern and New England loons.

Loon Vocalizations

Adult loons give four basic calls: wail, tremolo, yodel, and hoot.

The yodel is a territorial call given only by male loons. The call begins with three notes that rise slowly and are followed by several undulating phrases. It communicates to any loons in the area I am a male loon, I’m on my territory, and I’m prepared to defend it.

The wail resembles a wolf howl. Individuals use this call to locate other loons. If you listen closely, you will hear a wailing loon saying, where are you?

The tremolo sounds like a quavering laugh. It is typically used when loons are disturbed or excited. A variation of the tremolo is the flight call, which is often given over lakes and is a loon’s way of requesting clearance for landing. If a loon on the lake responds with a yodel, the one in the air usually flies on to the next lake.

The hoot is a soft, one-note call loons use in close quarters to call to chicks, mates, or even other loons in a social flock. In social groups, the hoot can be thought of as the loon’s way of saying hi.