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.
Though loons are generally extremely awkward on land, red-throated loons have been known to travel long distances on land. When seriously disturbed, they may even move to a new pool with their chicks. It is the lightest and most agile species of the genus and it has the largest wing-beat amplitude, and only the red-throated loon can take off from the ground, or alight directly on it. After breeding, these loons move to coastal waters, and sometimes gather in large flocks in particularly rich feeding areas. At such localities, the birds roost and feed communally. Aggressive behavior may be observed here, but it doesn’t develop. They spend long hours caring for their plumage, and their elaborate bathing practices involve rigorous wing shaking, rolling, diving and somersaulting. Roosting takes place mainly on water, but can occasionally occur on land during the breeding season. The loon’s characteristic call is extremely loud and can be heard far away. It is used to proclaim the occupation of a territory. It sounds like a long, low-pitched whistle with some very clear notes interspersed. It is made by both mates at once. When disturbed or threatened, the red-throated loon produces a raven-like croaking call of warning. It also uses a short, frequently repeated, gooselike cackle, which it gives when flying over its own or neighboring territory. Red-throated loons have a variety of ritualized behaviors, including a series of stereotyped swimming ceremonies, which are performed by both partners.
Listen to the sound of Red-throated Loon
Copyright remark: Most sounds derived from xeno-canto
|wingspan min.:||91||cm||wingspan max.:||110||cm|
|size min.:||55||cm||size max.:||67||cm|
|incubation min.:||26||days||incubation max.:||28||days|
|fledging min.:||38||days||fledging max.:||28||days|
Loons are monogamous, forming long-term pair bonds. Pairs established from the previous season probably remain together throughout the winter, and start nesting early on after a minimal amount of display. Even newly formed pairs have simple courtship displays. Copulation takes place on dry land and is repeated frequently. It may begin on their day of arrival at the nest and continue until all eggs have been laid. The male selects the nest site.
Since loons have difficulty in walking, the site is always close to water. The nest is simply a heap of plant matter. Several pairs may build nests semi-colonially, especially when there are few tracts of suitable water within reach of their feeding areas. Thus they are tolerant of other pairs close by and only defend the area immediately surrounding the nest. However, if they are not breeding colonially, they may aggressively defend up to several hectares, including several non-nesting ponds.
Breeding starts in May in the south of the range, and in the north, timing depends on when spring thaw occurs. 1-3 eggs may be laid, but there are almost always 2. Incubation is 27 days and is performed by both partners, with the female spending more time on the nest than the male. Incubation starts when the first egg is laid. The resulting differences in age and size of the chicks means that when food is scarce, the older, larger chick gets more, and the youngest frequently starves to death within its first few days.
The chicks have dark brown down, and are paler below. By 2-3 weeks, they spend most of the time swimming, though they still rely on their parents for food until they are fully grown. Fledgling takes place at around 7 weeks. They are sexually mature at 2-3 years, and are known to have lived 23 years in the wild.
Nest failures due to predation are probably much more important than those due to human disturbance, because their range in North America, at least, does not overlap much with where humans live.
Gavia stellata is a widespread breeder across much of northern Europe, which accounts
for less than a quarter of its global breeding range. Its European breeding population
is relatively small (<92,000 pairs), and underwent a large decline between 1970-1990, notably in Russia and Fennoscandia. Although the species was stable overall during 1990-2000, with stable trends in most countries within its European range, its population has clearly not yet recovered to the level that preceded its decline.
This diver has a widespread breeding distribution in northern Eurasia and North America. The breeding population of the European Union, entirely restricted to the British Isles and Denmark, amounts to 1400 breeding pairs and seems to be increasing
Principal wintering areas in Europe: Atlantic and North Sea coasts around Britain and Ireland and from western Norway at least south to Brittany, with smaller numbers in Kattegat and Baltic, Black and Caspian Seas; small minority penetrate south into Bay of Biscay and, in cold winters, Mediterranean. Migration routes not well known. A few winter on larger lakes of central Europe, but many inland winter records probably sickly or storm-blown birds.