|[Noty - Informator] Notatki Autora|
|We were driving in a touring car to the Sólheimajökull glacier when we pasted a pond with a Red-throated Loon with young. I asked the driver to stop on the way back when the loon was still there. There were 15 people in the bus and I asked them if it was alright to stop on our way back. They all agree and so I could make some photos of this bird which I didn’t see before (and after). It was in a hurry and in bad weather conditions, so not the best quality, but I was very pleased.|
The Red-throated Loon or Red-throated Diver (Gavia stellata) is a migratory aquatic bird found in the northern hemisphere. It breeds primarily in Arctic regions, and winters in northern coastal waters. It is the most widely distributed member of the loon or diver family. The Red-throated Loon is the smallest and lightest of the world's loons. In winter, it is a nondescript bird, greyish above fading to white below. During the breeding season, it acquires the distinctive reddish throat patch which is the basis for its common name. Fish form the bulk of its diet, though amphibians, invertebrates and plant material are sometimes eaten as well. A monogamous species, the Red-throated Loon forms long-term pair bonds. Both members of the pair help to build the nest, incubate the eggs (generally two per clutch) and feed the hatched young.
The Red-throated Loon has a large global population and a significant global range, though some populations are declining. Oil spills, habitat degradation, pollution and fishing nets are among the major threats this species faces. Natural predators—including various gull species, and both red and Arctic foxes, will take eggs and young. The species is protected by a number of international treaties.
The Red-throated Loon is the smallest and lightest of the world's loon species, ranging from 53 to 69 cm in length with a 91–120 cm wingspan and weighing 1–2.7 kg. Like all loons, it is long-bodied and short-necked, with its legs set far back on its body. The sexes are similar in appearance, although males tend to be slightly larger and heavier than females. In breeding plumage, the adult has a dark grey head and neck (with narrow black and white stripes on the back of the neck), a triangular red throat patch, white underparts and a dark grey-brown mantle. It is the only loon with an all-dark back in breeding plumage. The non-breeding plumage is drabber with the chin, foreneck and much of the face white, the top of the head and back of the neck grey, and considerable white speckling on the dark mantle.
Its bill is thin, straight and sharp, and the bird often holds it at an uptilted angle. Though the colour of the bill changes from black in summer to pale grey in winter, the timing of the colour change does not necessarily correspond to that of the bird's overall plumage change. The nostrils are narrow slits located near the base of the bill, and the iris is reddish.
Like the other members of its genus, the Red-throated Loon is well-adapted to its aquatic environment: its dense bones help it to submerge, its legs—in their set-back position—provide excellent propulsion and its body is long and streamlined. Even its sharply pointed bill may help its underwater streamlining. Its feet are large, its front three toes are fully webbed, and its tarsus is flattened, which reduces drag and allows the leg to move easily through the water.
In flight, the Red-throated Loon has a distinctive profile; its small feet do not project far past the end of its body, its head and neck droop below the horizontal (giving the flying bird a distinctly hunchbacked shape) and its thin wings are angled back. It has a quicker, deeper wingbeat than do other loons.
The adult Red-throated Loon has a number of vocalisations, which are used in different circumstances. In flight, when passing conspecifics or circling its own pond, it gives a series of rapid yet rhythmic goose-like cackles - kaa-kaa-kaa or kak-kak-kak, at roughly five calls per second. Its warning call, if disturbed by humans or onshore predators, is a short croaking bark. A low-pitched moaning call, used primarily as a contact call between mates and between parents and young, but also during copulation, is made with the bill closed. The species also has a short wailing call - aarOOao…aarOOao…, which descends slightly in pitch and lasts about a second; due to strong harmonics surrounding the primary pitch, this meowing call is more musical than its other calls. Another call — a harsh, pulsed cooing that rises and falls in pitch, and is typically repeated up to 10 times in a row—is used in territorial encounters and pair-bonding, and by parent birds encouraging their young to move on land between bodies of water. Known as the "long call", it is often given in duet, which is unusual among the loons; the female's contribution is longer and softer than her mate's.
Habitat and distribution
The Red-throated Loon breeds primarily in the Arctic regions of northern Eurasia and North America (generally north of 50°N latitude), and winters in northern coastal waters, sometimes in groups of considerable size.
In North America, it winters regularly along both coasts, ranging as far south as the Baja California Peninsula and the Gulf of California in north-western Mexico
In Europe, it breeds in Iceland, northern Scotland, north-western Ireland (a few pairs only), Scandinavia and northern Russia, and winters along the coast as far south as parts of Spain; it also regularly occurs along major inland waterways, including the Mediterranean, Aegean and Black Seas, as well as large rivers, lakes and reservoirs.
Because its feet are located so far back on its body, the red-throated loon is quite clumsy walking on land; however, it can use its feet to shove itself forward on its breast. Young use this method of covering ground when moving from their breeding pools to larger bodies of water, including rivers and the sea. It is the only species of loon able to take off directly from land. If frightened, it may submerge until only its head or bill shows above the surface of the water.
Breeding and survival
The Red-throated Loon is a monogamous species which forms long-term pair bonds. Both sexes build the nest, which is a shallow scrape (or occasionally a platform of mud and vegetation) lined with vegetation and sometimes a few feathers, and placed within a half-metre of the edge of a small pond. The female lays two eggs (though clutches of one and three have also been recorded); they are incubated for 24–29 days, primarily by the female. If a clutch is lost (to predation or flooding, for example) before the young hatch, the red-throated loon usually lays a second clutch, generally in a new nest.
In the wild, the oldest known Red-throated Loon lived for more than two decades; it was found, oiled and dead, on a beach in Sweden 23 years and 7 months after it had been ringed (banded).
Source: parts of Wikipedia
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