Identification of Red-throated Loon

The Birder's Market | Resource | Birds of Britain and Europe ID Guide | Loons (Divers) | Red-throated Loon Gavia stellata |  Identification of Red-throated Loon

Red-throated Loon Gavia stellata

Red-throated Loon Gavia stellata

From Wikipedia
The Red-throated Loon (diver) is the smallest and lightest of the world's loon species, ranging from 55–67 centimetres (22–26 in) in length with a 91–110 centimetres (36–43 in) wingspan, and averaging 1.4 kilograms (3.1 lb) in weight. 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, 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.

One of the bird's North American folk names is pegging-awl loon, a reference to its sharply pointed bill, which resembles a sailmaker's awl (a tool also known as a "pegging awl" in New England).

When it first emerges from its egg, the young Red-throated Loon is covered with fine soft down feathers. Primarily dark brown to dark grey above, it is slightly paler on the sides of its head and neck, as well as on its throat, chest, and flanks, with a pale grey lower breast and belly. Within weeks, this first down is replaced by a second, paler set of down feathers, which are in turn replaced by developing juvenile feathers.


In flight, the hunchbacked profile of the Red-throated Loon is distinctive.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 divers.
Slightly smaller than Black-throated Diver.When studied at any distance appears to hold bill pointing slightly upwards.Dark red brown throat patch is unmistakable in summer plumage.Most commonly seen at sea on east coast of Britain in winter where it appears black and white.Feeding on fish they usually jump up slightly before diving.

UK Status
Population trends are not monitored by the BTO, but the UK Seabird Monitoring Programme shows that numbers at sample study areas in Shetland fluctuated during 1980-2003, with low points in 1980 and 2000 (Mavor et al. 2004). Complete surveys of Shetland indicated a decrease of 36% there between 1983 and 1994, however (Gibbons et al. 1997). Since in 1994 Shetland held 28-45% of the total UK population, this warrants amber listing for Red-throated Diver, in addition to its depleted status in Europe as a whole. Further information is available from the BTO web site by clicking here

Red-throated Loon in winter plumage.Quick IDRed-throated Loon in winter plumage.Quick ID

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Behaviour

Because its feet are located so far back on its body, the Red-throated Loon is not capable of 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.

The Red-throated Loon is a diurnal migrant, which travels singly or in loose groups, often high above the water. In eastern North America (and possibly elsewhere), it tends to migrate near the coast rather than farther offshore; Siberian populations travel for hundreds of miles over land en route to their southern European wintering grounds. It is a strong flier, and has been clocked at speeds between 75 and 78 kilometres per hour (47–49 mph). Like all members of its family, the Red-throated Loon goes through a simultaneous wing moult, losing all its flight feathers at once and becoming flightless for a period of 3–4 weeks. However, unlike other loons—which undergo this moult in late winter—the Red-throated Loon loses its ability to fly sometime between late summer and late autumn.

Breeding

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 (18 in) of the edge of a small pond. The female lays two eggs (though clutches of 1–3 have been recorded); they are incubated for 24–29 days, primarily by the female. The eggs, which are greenish or olive-brownish spotted with black, measure 75 by 46 millimetres (3.0 in × 1.8 in) and have a mass of 83 grams (2.9 oz), of which 8 percent is shell.Incubation is begun as soon as the first egg is laid, so they hatch asynchronously. The young birds are precocial upon hatching: downy and mobile with open eyes. Both parents feed them small aquatic invertebrates initially, then small fish for 38–48 days. Parents will perform distraction displays to lure predators away from the nest and young. Ornithologists disagree as to whether adults carry young on their backs while swimming with some maintaining that they do and others the opposite.

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).

Food and feeding

Like all members of its family, the Red-throated Loon is primarily a fish-eater, though it sometimes feeds on molluscs, crustaceans, frogs, aquatic invertebrates, insects, fish spawn or even plant material. It seizes rather than spears its prey, which is generally captured underwater.Though it normally dives and swims using only its feet for propulsion, it may use its wings as well if it needs to turn or accelerate quickly. Pursuit dives range from 2–9 metres (6.6–30 ft) in depth, with an average underwater time of about a minute. Its fish diet increases the Red-throated Loon's vulnerability to persistent organic pollutants and heavy metals, both of which bioaccumulate, thus potentially causing greater problems for long-lived species (such as the diver) at or near the top of the food chain.Its main diet has also led to several of the loon's folk names, including "sprat borer" and "spratoon".


Chicks are competent swimmers, able to accompany their parents soon after hatching.For the first few days after hatching, young Red-throated Loons are fed aquatic insects and small crustaceans by both parents. After 3–4 days, the parents switch to fish small enough for the young birds to swallow whole. By four weeks of age, the young can eat the same food—of the same size—as their parents do.Young birds may be fed for some time after fledging; adults have been seen feeding fish to juveniles at sea and on inland lakes in the United Kingdom, hundreds of kilometers from any breeding areas.

Taxonomy. Click here for free PDf
Flight Speed of Arctic and Red-throated Loons PDf
The use of wings and feet by diving birds PDF
Replacement clutches in the Red-throated Loon PDf

The Birder's Market | Resource | Birds of Britain and Europe ID Guide | Loons (Divers) | Red-throated Loon Gavia stellata |  Identification of Red-throated Loon

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