Loons, like ducks, geese and grebes, are waterbirds, but they are classified separately by scientists. Loons are reported to be among the oldest groups of birds still living today, with a history some think stretches back more than 50 million years. Their closest living relatives are penguins and the tube-nosed swimmers (Albatrosses and Shearwaters).

North America is home to five species of loon, including the Red-throated Loon (Gavia stellata), Pacific Loon (Gavia pacifica), Arctic Loon (Gavia arctica), Yellow-billed Loon (Gavia Adams) and Common Loon (Gavia immer). The Common Loon is the most widespread and well-known species, and the only one that breeds in New Hampshire and the lower 48 states.

Body Form and Plumage of Common Loons

The Common Loon in summer is very striking with its black-and-white checkered back, glossy black head, and characteristic white necklace around the throat. The white feathers of the belly and wing linings are present year-round, but all loons have grayish feathers in the winter. Immature loons resemble adults in winter plumage.

Both males and females look the same, although males are generally larger. Adults are large-bodied, weighing from 2.7 to over 6.3 kilograms 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. In flight, loons can be recognized by their humpbacked profile, with head and neck held low and feet projecting beyond the tail.

The skeleton and muscular system of a loon are designed for swimming and diving. Their legs are placed far back on their body, allowing for excellent movement in water but making them ungainly on land. Their head can be held directly in line with their neck during diving to reduce drag, and their legs have powerful muscles for swimming. Many bones of the loon's body are solid, rather than hollow like those of other birds. These heavy bones make loons less buoyant and help loons to dive. The loon's large webbed feet, not their wings, provide propulsion underwater.

A Day in the Life of a Loon

Loons spend their days hunting, feeding, resting, preening, and caring for young. 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.

Loons spend long rest periods motionless on the water. They may rouse themselves to stretch a leg or wing at intervals, occasionally comically waggling a foot above water. Loons peer underwater and move their heads from side to side to locate prey. During dives, loons compress their feathers and force air from between their feathers and from the air sacs in the body. Losing air also allows loons to quietly sink below the water's surface to avoid danger.

Adult loons may fly to different lakes to feed, but 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; when it's calm they 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 70 m per hour.

Common Loons spend little time on land and literally 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. When returning to the water, the loon slides in along its breast and stomach. At night, loons sleep over deeper water, away from land, for protection from predators.

The Loon's Family and Social Life

In spring, loons arrive on northern lakes 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. However, banding studies have shown that loons will sometimes switch mates after a failed nesting attempt and even between nesting attempts 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 to mate. 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. The same sites are often used from year to year. Loons will use whatever materials are on hand to build their nests; pine tree needles, leaves, grass, moss and other vegetation have been found in loon nests. Sometimes clumps of mud and vegetation are collected from the lake bottom to build the nest. Both the male and female help with nest building and with incubation, which usually lasts 26-31 days. If the eggs are lost, the pair may Ernest, often in the same general location.

Usually one or 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' back to rest, conserve heat, and avoid predators such as large carnivorous fish, snapping turtles, gulls, eagles and crows. After their first day or two of life, the chicks do not return to the nest.

Chicks are fed exclusively by their parent for the first few weeks of life, and up until eight weeks of age, the adults are with them most of the time. 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. Early in their life, chicks are fed small food items including snails, small fish, crayfish, minnows, and some aquatic vegetation. As they grow, they are fed more fish. At migration time, the young are able to look after themselves. The adults generally leave first, flying from the breeding lakes to the ocean coast from Maine to Florida. The young follow on their own, often as long as a month later. They will not return to their natal lakes until they are three or four years old and are ready to breed.

Although they are thought of as solitary birds, loons sometime gather into small groups in the summer. In September, group feeding is quite common as loons gather on larger lakes during migration. Loons are usually found in groups on their ocean 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 to communicate with their families and other loons; these are the tremolo, wail, yodel and hoot.

The tremolo is also known as the "crazy laugh." It is used for a variety of purposes, such as to signal alarm or worry and to denote annoyance or greeting.

The wail call sounds much like a wolf's howl. 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 and can last up to six seconds. It is used by the male to defend his 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 loon and can be used to identify individual loons.

The hoot is a one-note call that sounds more like "hot." It is mainly used by family members to locate each other and check on their well-being.

SELECT A CALL BELOW TO HEAR THE CALL OF THE LOON.