Red-throated loon

Red-throated diver
Adult in breeding plumage and recently hatched young
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Gaviiformes
Family: Gaviidae
Genus: Gavia
Species: G. stellata
Binomial name
Gavia stellata
(Pontoppidan, 1763)
Red-throated loons breed in the northern regions of North America and Eurasia.
  Breeding summer visitor
  Winters at sea or great lakes
Synonyms

Colymbus stellatus Pontoppidan, 1763
Colymbus lumme Brünnich, 1764
Colymbus septentrionalis Linnaeus, 1766
Gavia lumme Forster, 1788
Colymbus mulleri Brehm, 1826
Urinator lumme Stejneger, 1882

The red-throated loon or red-throated diver (Gavia stellata) is a migratory aquatic bird found in the northern hemisphere. The most widely distributed member of the loon or diver family, it breeds primarily in Arctic regions, and winters in northern coastal waters. Ranging from 55–67 centimetres (22–26 in) in length, 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.

Taxonomy and etymology

First described by Danish naturalist Erik Pontoppidan in 1763, the red-throated loon is a monotypic species, with no distinctive subspecies despite its large Holarctic range.[2] Pontoppidan initially placed the species in the now-defunct genus Colymbus, which contained grebes as well as loons. By 1788, however, German naturalist Johann Reinhold Forster realized that grebes and loons were different enough to warrant separate genera, and moved the red-throated loon (along with all other loon species) to its present genus.[3] Its relationship to the four other loons is complex; although all belong to the same genus, it differs more than any of the others in terms of morphology, behaviour, ecology and breeding biology,[2] and may be the basal lineage of the genus.[4] It is thought to have evolved in the Palearctic, and then to have expanded into the Nearctic.[2]

The genus name Gavia comes from the Latin for "sea mew", as used by ancient Roman naturalist Pliny the Elder.[5] The specific epithet stellata is Latin for "set with stars" or "starry",[6] and refers to the bird's speckled back in its non-breeding plumage.[5] "Diver" refers to the family's underwater method of hunting for prey, while "red-throated" is a straightforward reference to the bird's most distinctive breeding plumage feature. The word "loon" is thought to have derived from the Swedish lom, the Old Norse or Icelandic lómr, or the Old Dutch loen, all of which mean "lame" or "clumsy", and is a probable reference to the difficulty that all loons have in moving about on land.[7]

Description

A grey and white bird swims in water.
An adult in non-breeding plumage shows the speckled back which gives the bird its specific name.

The red-throated loon is the smallest and lightest of the world's loon species, ranging from 53 to 69 cm (21 to 27 in) in length[nb 1][9] with a 91–120 cm (36–47 in) wingspan,[9][10] and weighing 1–2.7 kg (2.2–6.0 lb).[9] Like all loons, it is long-bodied and short-necked, with its legs set far back on its body.[11] The sexes are similar in appearance, although males tend to be slightly larger and heavier than females.[2] 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.[12] It is the only loon with an all-dark back in breeding plumage.[13] 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.[12]

Its bill is thin, straight and sharp, and the bird often holds it at an uptilted angle.[12] 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,[11] and the iris is reddish.[14] 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).[15]

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.[16]

Adult in breeding plumage in Iceland
Dark grey fuzzy-looking chick floats on water.
Very young birds are covered with dark brown or grey down feathers.

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.[14] The juvenile's plumage is similar to that of the adult, though with a few distinguishing features. It has a darker forehead and neck, with heavy speckling on the sides of the neck and the throat. Its back is browner and less speckled, and its underparts are tinged with brown. Its eyes are reddish-brown, and its beak is a pale grey. Though some young birds hold this plumage until mid-winter, many quickly become virtually indistinguishable from adults, except for their paler bills.[12]

diagram of silhouette of red-throated loon in flight
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 loons.[17]

Voice

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.[18] Known as the "long call", it is often given in duet, which is unusual among the loons;[19] the female's contribution is longer and softer than her mate's.[18]

Young have a shrill closed-bill call, which they use in begging and to contact their parents. They also have a long call used in response to (and similar to that of) the long call of adults.[18]

Similar species

At medium to close range, an adult red-throated loon in either breeding or non-breeding plumage is usually easily recognised. However, in certain light conditions, at certain times in its moulting cycle or at greater distances, it may be mistaken for another species—most commonly the black-throated loon, but also occasionally the great crested grebe. It shows more white on the head and neck than does the black-throated loon, and—provided it is not sitting low in the water—tends to show more white on the flanks as well. If it is sitting lower in the water, so that the white on the flanks is reduced to a patch on the rear flank (thus resembling the pattern of the black-throated loon), that patch tends to be less clearly defined than the comparative patch on the black-throated.[20]

Habitat and distribution

aerial view of tundra, with numerous small lakes dotting the ground
The red-throated loon breeds primarily in coastal tundra, often on very small lakes.

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,[21] sometimes in groups of considerable size. More than 4,400 spend the winter in a loose concentration on the eastern part of the German Bight, for example.[22] Unlike other loons, it regularly uses very small freshwater lakes as breeding sites.

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; it has been recorded as a vagrant in the interior Mexican state of Hidalgo.[23] Some of its folk names in north-eastern North America—including cape race, cape brace, cape drake and cape racer, as well as corruptions such as scapegrace—originated from its abundance around Cape Race, Newfoundland.[24] 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.[25] It has occurred as a vagrant as far south as Morocco, Tunisia and the Gambia.[1] In Asia, it breeds in the northern stretches of Siberia, and winters along the Pacific coast as far south as China, Japan and Taiwan. It has occurred as a vagrant in Mongolia.[1]

Behaviour

Adult loon in breeding plumage, reared up on the water with its wings spread.
Among the loons, the red-throated loon is exceptional in its ability to take off from very small bodies of water.

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.[17] Young use this method of covering ground when moving from their breeding pools to larger bodies of water, including rivers and the sea.[26] It is the only species of loon able to take off directly from land.[27] If frightened, it may submerge until only its head or bill shows above the surface of the water.[28]

The red-throated loon is a diurnal migrant, which travels singly or in loose groups, often high above the water.[17] In eastern North America (and possibly elsewhere), it tends to migrate near the coast rather than farther offshore;[29] Siberian populations travel for hundreds of miles over land en route to their southern European wintering grounds.[30] It is a strong flier, and has been clocked at speeds between 75 and 78 kilometres per hour (47 and 48 mph).[31] 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 three to four 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.[32]

Food and feeding

Two small fuzzy blackish chicks—one swallowing a silver fish—float on water beside a larger bird with a black back and grey neck.
Once they are 3–4 days old, the young are fed fish—which can be quite large compared to the size of the chick.

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.[21] It seizes rather than spears its prey, which is generally captured underwater.[33] 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.[34] Pursuit dives range from 2–9 m (6.6–29.5 ft) in depth, with an average underwater time of about a minute.[21] 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 loon) at or near the top of the food chain.[35] Its main diet has also led to several of the loon's British folk names, including "sprat borer" and "spratoon".[36]

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.[37] 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 kilometres from any breeding areas.[38][39]

Breeding and survival

Eggs, Collection Museum Wiesbaden
Small fuzzy black chick floats beside a larger bird on calm water with a muddy bank and tall grass in the background
Chicks are competent swimmers, able to accompany their parents soon after hatching.

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 one and three have also 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 mm × 46 mm (3.0 in × 1.8 in) and have a mass of 83 g (2.9 oz), of which 8% is shell.[33][40] Incubation is begun as soon as the first egg is laid, so they hatch asynchronously. 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.[41] 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.[33] Ornithologists disagree as to whether adults carry young on their backs while swimming with some maintaining that they do[33] and others the opposite.[9]

In the wild, the oldest known red-throated loon lived for more than two decades;[21] it was found, oiled and dead, on a beach in Sweden 23 years and 7 months after it had been ringed (banded).[42]

Conservation status and threats

Although the red-throated loon is not a globally threatened species, as it has a large population and a significant range, there are populations which appear to be declining. Numbers counted in U.S. Fish and Wildlife Service surveys in Alaska show a 53% population decline between 1971 and 1993, for example,[43] and counts have dropped in continental Europe as well.[44] In Scotland, on the other hand, the population increased by some 16% between 1994 and 2006, according to surveys done by the Royal Society for the Protection of Birds and Scottish Natural Heritage.[44] In 2002, Wetlands International estimated a global population of 490,000 to 1,500,000 individuals; global population trends have not been quantified.[1]

The red-throated loon is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies;[45] in the Americas, it is protected by the Migratory Bird Treaty Act of 1918.[46] Oil spills, habitat degradation, and fishing nets are among the main threats this species faces.[9] Because it tends to migrate close to shore—generally within 20 kilometres (12 mi) of land—it may be detrimentally affected by the construction of near-shore wind farms;[47] studies indicate a high level of avoidance of wind farm areas, though deaths due to direct strikes with the turbines appear to be uncommon.[48] High levels of mercury in the environment have led to reproductive failures in some areas, including parts of Sweden.[49] Studies in Sweden have also shown that they may be adversely impacted by the acidification of lakes, as the fish on which they prey are susceptible to low pH.[50] On the breeding grounds, Arctic and red foxes are major predators of eggs,[51] while great skuas, Arctic skuas and various species of Larus gulls (including great black-backed gulls and glaucous gulls)[52][53] are predators of both eggs and young.[54]

The species is known to serve as host for at least 51 species of parasites, most of which are roundworms (nematodes), flatworms (digeneans) and tapeworms (cestodes) carried internally; a single species of louse is its only known external parasite.[55] It is also known to sometimes carry significant populations of diatoms (microscopic phytoplankton) on its contour feathers.[56] The red-throated loon is susceptible to avian influenza[57] and Type E botulism,[58] and is regularly killed by the ingestion of neurotoxins produced by "red tide" algal blooms.[59] During a 2007 bloom, large numbers of the birds also died of hypothermia, after their plumages became matted by a protein byproduct of the algae, which reduced the insulating properties of their feathers.[60]

In human culture

Greyish bird with white speckles on its back and a sharply pointed grey bill floats on water
Juveniles have fewer speckles on their backs and darker necks than adults do.

Used as a food source since prehistoric times,[61][62] the red-throated loon is still hunted by indigenous peoples in some parts of the world today.[63] Eggs as well as birds are taken, sometimes in significant numbers; during one study on northern Canada's Igloolik Island, 73% of all red-throated loon eggs laid within the 10 km2 (3.9 mi2) study site over two breeding seasons were collected by indigenous inhabitants of the island.[64] In some parts of Russia, red-throated loon skins were traditionally used to make caps and various clothing decorations, including collars.[65] The species was also central to the creation mythologies of indigenous groups throughout the Holarctic.[66] According to the myth—which varies only slightly between versions, despite the sometimes-vast distances that separated the groups who believed it—the loon was asked by a great shaman to bring up earth from the bottom of the sea. That earth was then used to build the world's dry land.[66][67]

As recently as the 1800s, the behaviour of the red-throated loon was used to forecast the weather; according to the conventional wisdom of the time, birds flying inland or giving short cries predicted good weather, while those flying out to sea or giving long, wailing cries predicted rain.[40][44] In the Orkney and Shetland islands of Scotland, the species is still known as the "rain goose" in deference to its supposed weather-predicting capabilities.[44] The people of the Faroe Islands believed that if the red-throated loon miaowed like a cat, then rain was imminent, while a call of gaa-gaa-gaa or turkatrae-turkatrae predicted fine weather.[68]

Bhutan, Japan, Åland (an autonomous region of Finland), and the Union of the Comoros have issued stamps featuring the red-throated loon.[69]

Notes

  1. ↑ By convention, length is measured from the tip of the bill to the tip of the tail on a dead bird (or skin) laid on its back.[8]

References

  1. 1 2 3 4 BirdLife International (2012). "Gavia stellata". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013.
  2. 1 2 3 4 Carboneras 1992, p. 162
  3. ↑ Allen, J. A. (July 1897). "The Proper Generic Name of the Loons" (PDF). The Auk. 14 (3): 312–313. doi:10.2307/4068646. JSTOR 4068646.
  4. ↑ Boertmann, D. (1990). "Phylogeny of the divers, family Gaviidae (Aves)". Steenstrupia. 16: 21–36.
  5. 1 2 Johnsgard, Paul A. (1987). Diving Birds of North America. University of Nevada–Lincoln. ISBN 0-8032-2566-0.
  6. ↑ Simpson, Donald Penistan (1979). Cassell's Latin Dictionary (5th ed.). London: Cassell Ltd. p. 883. ISBN 0-304-52257-0.
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  8. ↑ Cramp 1997, p. 3
  9. 1 2 3 4 5 "All About Birds: Red-throated Loon Life History". Cornell Lab of Ornithology. Retrieved 20 October 2011.
  10. ↑ Svensson, Lars; Grant, Peter (1999). Collins Bird Guide. London: HarperCollins. pp. 12–13. ISBN 0-00-219728-6.
  11. 1 2 Cramp 1977, p. 42.
  12. 1 2 3 4 Cramp 1977, p. 43.
  13. ↑ Carboneras 1992, p. 163.
  14. 1 2 Cramp 1977, p. 49.
  15. ↑ Cassidy, Frederic Gomes; Hall, Joan Houston (2002). Dictionary of American Regional English: Volume IV, P–Sk. Cambridge, Massachusetts: Harvard University Press. p. 84. ISBN 0-674-00884-7.
  16. ↑ Sibley, David; Elphick, Chris; Dunning Jr., John B., eds. (2001). The Sibley Guide to Bird Life & Behaviour. London: Christopher Helm. pp. 124–25. ISBN 0-7136-6250-6.
  17. 1 2 3 Sibley, David (2000). The Sibley Guide to Birds. New York: Alfred A. Knopf. p. 23. ISBN 0-679-45122-6.
  18. 1 2 3 Cramp 1977, p. 48.
  19. ↑ Carboneras 1992, p. 164.
  20. ↑ Appleby, R. H.; Madge, Steve; Mullarney, Killian (August 1986). "Identification of divers in immature and winter plumages". British Birds. 79 (8): 365–91.
  21. 1 2 3 4 Carboneras 1992, p. 171.
  22. ↑ von Nordheim, Henning; Boedeker, Dieter; Krause, Jochen (2006). Progress in Marine Conservation in Europe: Natura 2000 Sites in German Offshore Waters. Berlin: Springer. p. 85. ISBN 978-3-540-33291-6.
  23. ↑ Howell, Steve N. G.; Sophie Webb (1995). A Guide to the Birds of Mexico and Northern Central America. Oxford University Press. p. 92. ISBN 0-19-854012-4.
  24. ↑ Cassidy, Frederic Gomes; Hall, Joan Houston (1985). Dictionary of American Regional English: Volume1, A–C. Harvard University Press. p. 539. ISBN 0-674-20511-1.
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  26. ↑ Haviland, Maud D. (March 1915). "On the Method of Progression on Land of a Young Red-throated Diver". British Birds. 8 (10): 241–43.
  27. ↑ Mead-Waldo, E. G. B. (November 1922). "Habits of the Red-throated Diver". British Birds. 16 (6): 172–73.
  28. ↑ Cramp 1977, p. 44.
  29. ↑ Powers, Kevin D.; Cherry, Jeffrey (1983). "Loon migrations off the coast of the northeastern United States" (PDF). Wilson Bulletin. 95 (1): 125–32.
  30. ↑ Carboneras 1992, p. 168.
  31. ↑ Davis, Rolph A. (January 1971). "Flight speed of Arctic and Red-throated Loons" (PDF). The Auk. 88 (1): 169. doi:10.2307/4083974. JSTOR 4083974.
  32. ↑ Wolfenden, Glen E. (1967). "Selection for a Delayed Simultaneous Wing Molt in Loons (Gaviidae)" (PDF). The Wilson Bulletin. 79 (4): 416–20.
  33. 1 2 3 4 Ehrlich, Paul R.; Dobkin, David S.; Wheye, Darryl; Pimm, Stuart L. (1994). The Birdwatcher's Handbook. Oxford, UK: Oxford University Press. p. 2. ISBN 0-19-858407-5.
  34. ↑ Townsend, Charles W. (July 1909). "The Use of the Wings and Feet by Diving Birds" (PDF). The Auk. 26 (3): 234–48. doi:10.2307/4070795. JSTOR 4070795.
  35. ↑ Dickson, D. Lynne; Gilchrist, H. Grant (2002). "Status of Marine Birds of the Southeastern Beaufort Sea" (PDF). Arctic. 55 (supp. 1): 46–58.
  36. ↑ Cocker, Mark; Mabey, Richard (2005). Birds Britannica. London, UK: Chatto & Windus. p. 3. ISBN 0-7011-6907-9.
  37. ↑ Cramp 1977, p. 46
  38. ↑ Hart, Alan S.; Jardine, David C. & Colin Hewitt (June 1998). "Red-throated Diver feeding young in October". British Birds. 91 (6): 231.
  39. ↑ Barber, S. C. (June 2002). "Red-throated Diver feeding young in November". British Birds. 95 (6): 313.
  40. 1 2 "Red-throated Diver". British Trust for Ornithology. Retrieved 27 June 2008.
  41. ↑ Schamel, Douglas; Tracy, Diane M. (Summer 1985). "Replacement clutches in the Red-throated Loon" (PDF). Journal of Field Ornithology. 56 (3): 282–283.
  42. ↑ Staav, Roland; Fransson, Thor (2008). "European Longevity Records". EURING: The European Union for Bird Ringing. Retrieved 14 July 2009.
  43. ↑ Groves, Deborah J.; Conant, Bruce; King, Rodney J.; Hodges, John I.; King, James G. (1996). "Status and trends of loon populations summering in Alaska, 1971–1993" (PDF). The Condor. 98 (2): 189–95. doi:10.2307/1369136.
  44. 1 2 3 4 "Rise in divers mystifies experts". BBC News. 7 September 2007. Retrieved 7 September 2007.
  45. ↑ "Species". Agreement on the Conservation of African-Eurasian Migratory Waterbirds. Retrieved 29 December 2015.
  46. ↑ "Birds Protected by the Migratory Bird Treaty Act". US Fish and Wildlife Service. Retrieved 29 June 2008.
  47. ↑ Stienen, Eric W.M.; Waeyenberge, Van; Kuijken, Eckhart; Seys, Jan (2007). "Trapped Within the Corridor of the Southern North Sea: The Potential Impact of Offshore Wind Farms on Seabirds". In de Lucas, Manuela; Janss, Guyonne F.E.; Ferrer, Miguel. Birds and Wind Farms: Risk Assessment and Mitigation (PDF). London: Quercus. pp. 71–80.
  48. ↑ Halley, D.J.; Hopshaug, P. "Breeding and overland flight of red-throated divers Gavia stellata at Smøla, Norway, in relation to the Smøla wind farm" (PDF). Norwegian Institute of Nature Research. Retrieved 26 July 2009.
  49. ↑ Eriksson, M.O.G.; Johansson, I.; Ahlgren, C.G. (1992). "Levels of mercury in eggs of red-throated diver Gavia stellata and black-throated diver G. arctica in southwest Sweden". Ornis Svecica. 2 (1): 29–36.
  50. ↑ Eriksson, Mats O. G (1994). "Susceptibility to freshwater acidification by two species of loon: Red-throated Loon (Gavia stellata) and Arctic Loon (Gavia arctica) in southwest Sweden". Hydrobiologia. 279–280 (1): 439–444. doi:10.1007/BF00027875.
  51. ↑ Schamel, Douglas; Tracy, Diane (Summer 1985). "Replacement Clutches in the Red-throated Loon" (PDF). Journal of Field Ornithology. 56 (3): 282–83.
  52. ↑ Serle, W. (January 1936). "Mortality amongst Red-throated Divers". British Birds. 29 (1): 81–82.
  53. ↑ Eberl, Christine; Picman, Jaroslav (July–September 1993). "Effect of Nest-site Location on Reproductive Success of Red-throated Loons (Gavia stellata)" (PDF). The Auk. 110 (3): 436–444. doi:10.2307/4088408. JSTOR 4088408.
  54. ↑ Booth, C. J. (January 1978). "Breeding success of Red-throated Divers". British Birds. 71 (1): 44.
  55. ↑ Storer, Robert W. (2002). The Metazoan Parasite Fauna of Loons (Aves: Gaviiformes), Its Relationship to the Birds' Evolutionary History and Biology, and a Comparison with the Parasite Fauna of Grebes (PDF). Museum of Zoology, University of Michigan. p. 37. ISSN 0076-8405.
  56. ↑ Croll, Donald A.; Holmes, Robert W. (October 1982). "A Note on the Occurrence of Diatoms on the Feathers of Diving Seabirds" (PDF). Auk. 99: 765–66.
  57. ↑ "Red-throated Loon – BirdLife Species Factsheet". BirdLife International. Retrieved 14 July 2009.
  58. ↑ Leighton, F. A. (2007). "Type E Botulism in Birds". Canadian Cooperative Wildlife Health Centre. Retrieved 14 July 2009.
  59. ↑ "Quarterly Wildlife Mortality Report". USGS. 2007. Retrieved 14 July 2009.
  60. ↑ Jessup, David A.; Miller, Melissa A.; Ryan, John P.; Nevins, HM; et al. (23 February 2009). Bennett, Peter M., ed. "Mass Stranding of Marine Birds Caused by a Surfactant-Producing Red Tide". PLoS ONE. 4 (2): e4550. doi:10.1371/journal.pone.0004550. PMC 2641015Freely accessible. PMID 19234604.
  61. ↑ Gordon, Bryan C.; Savage, Howard (1974). "Whirl Lake: A Stratified Indian Site Near the Mackenzie Delta" (PDF). Arctic. 27 (3): 175–88. doi:10.14430/arctic2872.
  62. ↑ Tagliacozzo, Antonio; Gala, Monica (November 2002). "Exploitation of Anseriformes at two Upper Palaeolithic sites in Southern Italy: Grotta Romanelli (Lecce, Apulia) and Grotta del Santuario della Madonna a Praia a Mare (Cosenza, Calabria)" (PDF). Acta zoologica cracoviensia. 45 (special issue): 117–31.
  63. ↑ Bird, Louis; Brown, Jennifer S.H. (2005). Telling Our Stories: Omushkego Legends and Histories from Hudson Bay. Broadview Press. ISBN 1-55111-580-8.
  64. ↑ Forbes, Graham; Robertson, Kelly; Ogilvie, Carey; Seddon, Laura (September 1992). "Breeding Densities, Biogeography, and Nest Predation of Birds on Igloolik Island, NWT" (PDF). Arctic. Peterborough, Ontario. 45 (3): 295–303. doi:10.14430/arctic1404.
  65. ↑ "Red-throated Loon". Birds of North America Online. Cornell Laboratory of Ornithology and the American Ornithologists' Union. Retrieved 27 March 2008. (Registration required)
  66. 1 2 Köngäs, Elli Kaija (Spring 1960). "The Earth-Diver (Th. A 812)". Ethnohistory. 7 (2): 151–80. doi:10.2307/480754. JSTOR 480754. (Registration required)
  67. ↑ Lutwack, Leonard (1994). Birds in Literature. University Press of Florida. p. 82. ISBN 0-8130-1254-6.
  68. ↑ Armstrong, Edward A. (1970) [1958]. The Folklore of Birds. New York, NY: Dover Publications. pp. 62–63. ISBN 0-486-22145-8.
  69. ↑ Scharning, Kjell. "Stamps showing Red-throated Loon Gavia stellata". Theme Birds on Stamps. Retrieved 23 July 2016.

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