Loons are water birds like ducks, geese, and grebes, but they are classified separately by scientists. The five species are:
- Red-throated Loon — Gavia stellata
- Pacific Loon — Gavia pacifica
- Arctic Loon — Gavia arctica
- Yellow-billed Loon — Gavia adamsii
- Common Loon — Gavia immer
The Common Loon is the species best known to most of us, as its breeding range lies across most of Canada. All five species of loons migrate to warmer areas around the Gulf of Mexico and on the east and west coasts of North America to winter, and return to northern lakes to breed when the ice melts in spring.
Body Form and Plumage
The Common Loon in summer is very striking with its black-and-white checkered back, glossy black head, white belly and wing lining, and a characteristic white necklace around the throat. All loons have grayish feathers in the winter, and immature birds tend to resemble adult birds in winter plumage. The white feathers of the belly and wing lining are present year-round.
Loons’ habit of swimming low in the water helps to distinguish them from other waterbirds, such as ducks and geese. Loons most resemble the grebes but can be identified by their larger size, thicker necks, and longer bills. In-flight, loons can be recognized by their humpbacked profile, with head and neck held low and feet pressed back towards the body and projecting beyond the tail.
Both males and females look the same, although males are generally larger. Adults are large-bodied, weighing from 2.7 to over 6.3 kg and measuring almost a meter from bill tip to outstretched feet. The bill is quite large, averaging 75 mm in length, and is black in color throughout the year.
The skeleton and muscular systems are designed for swimming and diving. Loons are streamlined. Their legs are placed far back on their body, allowing for excellent movement in the water but making them ungainly on land. The head can be held directly in line with the neck during diving to reduce drag, and the legs have powerful muscles for swimming. Many bones of the loon’s body are solid, rather than hollow like other birds’, aiding in diving ability. During dives, the large webbed feet provide all of the propulsion and the wings are held tight unless they are used to help make sharp turns while chasing prey.
Loons spend their time hunting, feeding, resting, preening, and caring for the young. They are predators; their diet in summer consists of fish, crayfish, frogs, snails, salamanders, and leeches. Adult loons prefer fish to other food, and seem to favor perch, suckers, catfish, sunfish, smelt, and minnows. The life expectancy of the loon maybe 15-30 years.
The bird spends long rest periods motionless on the water. It may rouse itself to stretch a leg or wing at intervals, occasionally comically waggling a foot. When swimming on top of the water it will sit erect with the neck slightly curved. The loon will peer underwater, moving its head from side to side to locate prey. It then aims and dives quickly. It will stay underwater for almost a minute and can dive to depths of 80 m. During the dive, feathers are compressed and the air is forced from between the feathers and from the air sacs in the body. Loss of air from the air sacs also allows the loon to quietly sink below the water surface to avoid danger.
Adult loons may fly to different lakes to feed. The adaptations that make loons such efficient divers also make them heavy and slow to take wing. To take off from a lake, loons run along the surface into the wind. The distance needed to gain flight depends on wind speed; in calm times the birds may run as far as several hundred meters before they gain enough speed to take off. Once in the air, the loon’s relatively small wingspan (130-140 cm) carries it at average speeds of 120 km per hour during migration. The wings beat quickly to carry the large body and have a high degree of curvature to provide lift.
Common Loons spend little time on land and have to pull themselves onto land to nest. They generally move one foot at a time to walk, shuffling along with their breast close to the ground. On return to the water, the loon slides in along its breast and stomach. At night, loons sleepover deeper water, away from land for protection from predators.
Family and Social Life
Loons arrive in pairs on northern lakes in the spring as soon as the ice thaws. Loons are solitary nesters. Small lakes, generally those between 5 and 50 ha, can accommodate one pair of loons. Larger lakes may have more than one pair of breeding loons, with each pair occupying a bay or section of the lake. Until recently, loons were thought to mate for life. Banding studies have shown that loons will sometimes switch mates after a failed nesting attempt, even between nestings in the same season. Courtship and mating are a quiet time, with the pair swimming and making short dives together. Eventually, the male leads the female to a suitable spot on land for copulation. Nest building then begins
Loons build their nests close to the water, with the best sites being completely surrounded by water, such as on an island, muskrat house, half-submerged log, or sedge mat. Generally, the birds can slip directly from the nest to water. The same sites are often used from year to year. Loons will use whatever materials are on hand to build their nests: tree needles, leaves, grass, moss, and other vegetation have been found under loon eggs. If material is not handy, loons will lay their eggs directly on the mud or rock substrate. Sometimes clumps of mud and vegetation are collected from the lake bottom to build the nest. Both the male and female help in nest building and with incubation, which lasts until hatching, usually 26-31 days. If the eggs are lost, the pair may renest, often in the same general location.
Usually, two eggs are laid in June, and towards the end of the month loon chicks covered in brown-black down appear on the water. Loon chicks can swim right away, but spend some time on their parents’ backs to rest, conserve heat, and avoid predators such as large carnivorous fish, snapping turtles, gulls, eagles, and crows. After their first day or two in the water, the chicks do not return to the nest.
Chicks are fed exclusively by their parents for the first few weeks of life, and up until eight weeks of age, the adults are with them most of the time, providing most food. After this time the chicks begin to dive for some of their own food and by 11 or 12 weeks of age, the chicks are providing almost all of their own food and may be able to fly. Chicks are fed small food items early in their life including snails, small fish, crayfish, minnows, and some aquatic vegetation. As they grow, they require more protein and usually are fed more fish, if available. At migration time, the young are able to look after themselves, and the adults generally leave first, with young following soon after.
Sometimes loons gather into small groups in the summer. In September, group feeding is quite common as loons gather on larger lakes while migrating. Loons are also usually found in groups on the wintering grounds.
The Voice of the Loon
Perhaps one of the most fascinating things about Common Loons is their haunting and variable voice. Loons are most vocal from mid-May to mid-June. They have four distinct calls which they use in varying combinations to communicate with their families and other loons. These are the tremolo, wail, yodel, and hoot.
- The tremolo sounds like a crazy laugh and is used for a variety of purposes, such as to signal alarm or worry and to denote annoyance or greeting.
- The wail is one of the loveliest of loon calls. It is used frequently during social interactions between loons and may be used to regain contact with a mate during night chorusing and in answering other loon tremolos.
- The yodel is given only by the male. It is a long, rising call with repetitive notes in the middle and can last up to six seconds. It is used by the male to defend territory and can be stimulated by another male entering a loon’s territory. Studies of recordings have shown that the yodel is different for each bird and can be used to identify individual loons.
- The hoot is a one-note call that sounds more like “hoo.” It is mainly used by family members to locate each other and check on their well-being.
This article is an excerpt from the North American Loon Fund website, however, the article is no longer available online. To find out more about loons click on the link to the NALF website.