The genus gavidae is formed by five species exclusively from the Northern Hemisphere. All of them are rather large birds, breeding in the arctic and boreal zone of Eurasia and North America. Although ranges overlap a great deal, identification is pretty straightforward. The bills are so distinctive that it is easy to tell them apart, with the exeption of the Pacific and Arctic Divers which are rather similar.
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.
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 metre from bill tip to outstretched feet. The bill is quite large, averaging 75 mm in length, and is black in colour throughout the year.
The skeleton and muscular system are designed for swimming and diving. Loons are streamlined. Their legs are placed far back on their body, allowing for excellent movement in 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.
Listen to the sound of Loon
Copyright remark: Most sounds derived from xeno-canto
|wingspan min.:||122||cm||wingspan max.:||148||cm|
|size min.:||73||cm||size max.:||88||cm|
|incubation min.:||24||days||incubation max.:||25||days|
|fledging min.:||70||days||fledging max.:||25||days|
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.
Common Loons spend most of the time on water 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. The loon returns to the water by sliding in along its breast and belly. At night, loons sleep over deeper water, away from land for protection from predators.
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-a clump of grass-like water plants. 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. Researchers have found tree needles, leaves, grass, moss, and other vegetation under loon eggs. If material is not handy, loons will lay their eggs directly on the mud or rock. 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, or warming the eggs, which lasts until hatching, usually 26 to 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 life expectancy of the loon may be 15 to 30 years.
This bird inhabits the lakes of the boreal regions of North America, Greenland and Island, moving to coastal waters in winter. The population of Greenland and Island – altogether about 3500-4000 birds – is wintering along the British and Norwegian coasts. Small numbers of individuals reach the coasts from Denmark to Portugal