Gavia stellata

Because red-throated divers lie deep in the water, only their dark grey back of their body is visible. With their short webbed feet located close to their tail end, they are terrific swimmers and divers, catching and consuming their prey underwater. Only larger prey are carried to the surface. This bird was used for predicting the weather on the Shetlands: flying inland or short cries meant good weather; flying to sea or long cries predicted wet weather.

Somewhat smaller (25 inches) and paler than the Common Loon (Gavia immer), the Red-throated Loon in summer is most easily identified by its gray head, dark bill, dark back, and conspicuous red throat patch. Winter Red-throated Loons are dark above and pale on the breast, throat, and head, slightly more so than winter Common Loons. Male and female Red-throated Loons are similar to one another in all seasons. The Red-throated Loon inhabits a large portion of Eurasia (where it is known as the Red-throated Diver) and North America. In the New World, this species breeds along the coasts of Canada and Alaska. Red-throated Loons breeding in North America spend the winter along the Pacific coast from southern Alaska south to Baja California and along the Atlantic Coast from Nova Scotia to northern Florida. In the Old World, this species breeds in Greenland, Iceland, northwestern Britain and Ireland, Scandinavia, and northern Russia, wintering south to the Mediterranean Sea and southern China. In summer, Red-throated Loons breed in lakes and ponds either on the tundra or in evergreen forests. During the winter, Red-throated Loons are found along the coast in near-shore waters and on large bays. On migration, this species may be found on large bodies of freshwater in the interior. Red-throated Loons primarily eat small fish, which they catch by diving. Due to the relative inaccessibility of their breeding grounds, most birdwatchers are more familiar with Red-throated Loons during the winter. At this time of year, Red-throated Loons are most easily observed out at sea through binoculars or spotting scopes, and may be seen floating low in the water, diving below the surface in pursuit of prey, or flying awkwardly close to the tops of the waves. This species is primarily active during the day.

Threat Status: Least concern

N Eurasia and n N Am.; winters to Caspian and Mediterranean.

Arctic Ocean, Belgian Exclusive Economic Zone, European waters (ERMS scope), Gulf of Maine, Gulf of Mexico, Mediterranean Sea, North West Atlantic, Polish Exclusive Economic Zone, Portuguese Exclusive Economic Zone, Spanish Exclusive Economic Zone, Swedish Exclusive Economic Zone, United Kingdom Exclusive Economic Zone, Wimereux

North America; winter range extends from the Scotian Shelf to Northern Florida

The Red-throated Loon is a migratory species which breeds in the Arctic Regions of the northern hemisphere generally breeding north of 50°, and wintering along the Pacific and Atlantic coasts of North America as far south as Florida and California (USA), on the coast of Portugal, in the Mediterranean Sea and Black Sea, and on the Pacific coast of Asia as far south as south-east China¹.

Holarctic, breeding far into the high Arctic, and winters mainly on the northern coasts of the Atlantic and Pacific. Also in the Great Lakes, and the Black, Caspian, and Mediterranian Seas.

Biogeographic Regions: nearctic (Native ); palearctic (Native ); arctic ocean (Native )

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) Breeding in North America occurs on Arctic coasts and islands from Alaska to Ellesmere Island, south along the Pacific coast through the Aleutian Islands to Queen Charlotte and Vancouver islands; inland to central Yukon, southern Mackenzie, northeastern Alberta, northern Saskatchewan, around Hudson Bay, and along the Atlantic coast to southeastern Quebec. In Eurasia, the breeding range extends from Greenland, Iceland, and Arctic islands and coasts south to the British Isles, southern Scandinavia, northern Russia, Lake Baikal, Sakhalin, the Kuril Islands, Kamchatka, and the Commander Islands (AOU 1998). During the nonbreeding season, the range in North America extends from the Aleutians south along the coast to northwestern Mexico; and from southern Newfoundland to northeastern Florida and the Gulf Coast; in Eurasia south to Mediterranean, Black, and Caspian seas, and along the western Pacific coast to China and Taiwan (AOU 1998).

Circumpolar, spreads south to 30°N in winter.

The red-throated loon is the smallest, slightest of the divers. It stands at 53-69 cm., and its wingspan ranges from 106-116 cm. During the breeding season, the upper body is a solid dark brown. The head and upper neck is grayish, with a large, glossy colored patch on the foreneck. It is white underneath and the tail is dark. In the winter, the face and foreneck are pure white, and the upper part is dark brownish and finely spotted with white. Males average slightly larger than females, and have a heavier head and bill. Its neck is thick, and the nostrils are narrow and elongated, as an adaptation to diving. The iris is reddish, especially in adults during the breeding season. The body is designed for swimming, with short, strong legs set far back on the body. The legs are perfect for moving through water, although this design makes walking on land difficult. The three front toes are webbed, and these loons have short, well-defined tails. They can vary their buoyancy in order to remain underwater, with the whole body submerged and only the eyes and bill visible above the surface. Adult loons shed their flight feathers simultaneously at the end of the breeding season and are thus unable to fly for several weeks. The body feathers are molted only in early spring and early autumn. (del Hoyo, Elliot, and Sargatal, 1992)

Average mass: 1816 g.

Length: 64 cm

Weight: 1551 grams

Length: 61 cm, Wingspan: 110 cm

See Stallcup (1994) for information on identification of North American loons.

Habitat and Ecology

Systems

• Terrestrial
• Freshwater
• Marine

It breeds mostly on fresh water, typically in fairly open moorland, and may occupy stretches of water of almost any size. It is often found to be nesting by small pools. It winters on inshore waters along sheltered coasts, occasionally inland.

Aquatic Biomes: lakes and ponds; rivers and streams; coastal

Depth range based on 5021 specimens in 1 taxon.
Water temperature and chemistry ranges based on 483 samples.

Environmental ranges
  Depth range (m): 0 - 0
  Temperature range (°C): 0.625 - 24.704
  Nitrate (umol/L): 0.440 - 12.040
  Salinity (PPS): 5.715 - 35.960
  Oxygen (ml/l): 4.690 - 8.325
  Phosphate (umol/l): 0.092 - 0.740
  Silicate (umol/l): 1.195 - 16.169

Graphical representation

Temperature range (°C): 0.625 - 24.704

Nitrate (umol/L): 0.440 - 12.040

Salinity (PPS): 5.715 - 35.960

Oxygen (ml/l): 4.690 - 8.325

Phosphate (umol/l): 0.092 - 0.740

Silicate (umol/l): 1.195 - 16.169
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

Comments: Ponds and lakes in coastal and alpine tundra, and coastal flats south of tundra (breeding); primarily bays, seacoasts and estuaries, less frequently on lakes and rivers (nonbreeding) (AOU 1983).

Nests on edges of lakes and ponds (typically small and shallow), usually on ground in shallow scrape or on mound of mud/plant material; or on hummock in shallow water. Nesting ponds average about 0.3-0.4 ha, may lack food source; 1-4 ponds/territory. In the Northwest Territories, most ponds used for nesting were 0.1-1.0 ha in surface area and 0.3-1.0 m deep; emergent vegetation covered an average of 17% of the pond surface area; over half of the ponds had >80% marshy shoreline; 68% of nests were along wet shorelines, 18% were on islands, and 10% were in shallow water offshore; nests tended to be in sites not exposed to wind-driven waves and were an average of 2 m from open water; most nests were platforms built with aquatic vegetative growth from the previous year (Dickson 1994). In the Northwest Territories, nests within 9 km of marine foraging areas had higher reproductive success than did nests farther away (Eberl and Picman 1993).

Winter: Coastal bays and estuaries Summer: Tundra lakes

Non-Migrant: No. All populations of this species make significant seasonal migrations.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.

Arrives in nesting areas around Beaufort Sea usually in early June (Johnson and Herter 1989). Common migrant off U.S. west coast April-June. Returns to U.S. Atlantic coast mainly in October, off California shores by September-October (Terres 1980). Large numbers may pass through the Great Lakes region in October.

Migrate singly or in small groups to coastal areas.

Red-throated loons prefer to forage in marine waters and never forage in their nesting pond, unlike other loons.

The red-throated loon obtains most of its food underwater, in dives that have been recorded at 2-9 meters, and average 1 minute. Prey is located visually, so these loons favor clear waters for foraging, and they do not fish at night. The prey consists of small or medium sized fish, including cod, herring, sprat, sculpins, and occasionally crustaceans, mollusks, frogs, fish spawn and insects. Food is usually swallowed before the loon surfaces. Their esophagus is relatively elastic, but a few have suffocated after swallowing too large a fish. When they find a suitable prey species in abundance, they will fully exploit it. (del Hoyo, Elliot and Sargatal, 1992)

Animal Foods: amphibians; fish; insects; mollusks; aquatic crustaceans

Primary Diet: carnivore (Piscivore )

Comments: Diet mainly fishes; also eats shrimps, snails, aquatic insects and some aquatic plants. When feeding young, often leaves nesting area to obtain fishes from larger lake or marine waters (Reimchen and Douglas 1984). Forages in shallow water.

Consists mostly of fish, also includes shrimp, crabs, snails, mussels, aquatic insects, leeches, frogs, and possibly plant material.

Gavia stellata is prey of:
Stercorarius
Larus hyperboreus
Alopex lagopus

Based on studies in:
Norway: Spitsbergen (Coastal)

This list may not be complete but is based on published studies.

Gavia stellata preys on:
Animalia
Diptera
Entomostraca
Rotifera
Tardigrada
Nematoda
Oligochaeta
Actinopterygii
Mollusca
Crustacea
Insecta
Amphibia

Based on studies in:
Norway: Spitsbergen (Coastal)

This list may not be complete but is based on published studies.

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: > 300

Comments: This species is represented by a large number of occurrences (subpopulations).

10,000 - 1,000,000 individuals

Comments: Alaska: statewide estimate 10,000 individuals; Canada: 12,000 individuals (surveyed areas only); Russian estimate: 71,000 individuals. (AK Loon and Grebe Working Group Meeting 2002). Estimates in West Palearctic: 2,000 pairs in Finland; circa 1,200-1,500 pairs in Scotland; 1,000 pairs in Iceland; 1,000 pairs in Norway; 10,000 in British waters (Hoyo et al. 1992).

Based on Christmas Bird Counts in North America, areas of highest winter density are eastern North Carolina, the Delaware Bay area, and between Point Arena and Point Reyes on the west coast (Root 1988). Relative abundance highest in North Carolina (246.38 birds per 100 survey hours; Sauer et al. 1996).

Somewhat gregarious when not breeding (Oberholser 1974). Gulls, jaegers, and/or arctic fox may cause significant loss of eggs and young in some areas (Johnsgard 1987).

Defends nesting territories of variable size. Sometimes an single pond is defended (e.g. 1.1 ha in Shetland Islands, Furness 1983), sometimes multiple ponds (Tuktoyaktuk Peninsula, NWT, Dickson 1993), sometimes several pairs share a larger lake (e.g. 5 pairs on a 76-hectare lake on Bathurst Island, Barr et al. 2000). Home range larger than breeding territory; individuals fly up to 14-20 kilometers away from nest site to forage (summarized by Barr et al. 2000). Merrie (1978) suggested that each breeding pair requires 2.5 square kilometers of foraging waters.

Comments: Activity may extend into twilight when adults feeding young (Reimchen and Douglas 1984).

Average lifespan
Status: wild: 23.0 years.

Maximum longevity: 23.7 years

Red-throated loons breed on freshwater lakes of the subarctic and boreal zones, with a strong preference for undisturbed sites. They readily settle on stretches of still water ranging in size from small pools to large, deep lakes, and sometimes even nest on sheltered coasts.

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.

Range eggs per season: 1 to 3.

Average time to hatching: 27 days.

Average time to independence: 7 weeks.

Range age at sexual or reproductive maturity (female): 2 to 3 years.

Range age at sexual or reproductive maturity (male): 2 to 3 years.

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); fertilization (Internal )

Average time to hatching: 28 days.

Average eggs per season: 2.

Nesting begins late May in south, late June or early July in far north; eggs are laid from early May to mid-July in British Columbia (Douglas and Reimchen 1988). Both sexes (mainly female) incubate 1-2 (usually 2) eggs 24-31 days. Young are tended by both parents, fly at about 8 weeks. First breeds probably at 2-3 years (Johnsgard 1987). Nest density in Alaska and Canada ranges up to 1.65 per sq km (Johnson and Herter 1989).

Nest sites are locates at small lakes, and territories are defended by both partners. Nest is built by both partners on shore or in shallows. It is reused year to year. 2 eggs incubated by both sexes for 24-29 days. Both parents care for the young. May mate for life.

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 12
Specimens with Barcodes: 17
Species With Barcodes: 1

The following is a representative barcode sequence, the centroid of all available sequences for this species.

There are 10 barcode sequences available from BOLD and GenBank.  Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.  See the BOLD taxonomy browser for more complete information about this specimen and other sequences.

Download FASTA File

Canada

Rounded National Status Rank: N5B,N4N : N5B: Secure - Breeding, N4N: Apparently Secure - Nonbreeding

United States

Rounded National Status Rank: N5B,N5N : N5B: Secure - Breeding, N5N: Secure - Nonbreeding

Year Assessed

Assessor/s

Reviewer/s

Contributor/s

Justification

History

• 2008
  Least Concern
• 2004
  Least Concern

Red-throated loons are fairly sensitive to human disturbance and will desert the breeding lake if there is too much human activity. Direct human disturbance causes most breeding failures. The red-throated loon is also affected in places by changes in water level. It may suffer seriously from acidification of breeding waters and heavy metal pollution. It is highly vulnerable to oil spills, especially near rich fishing grounds where large congregations of birds may form in winter. Diver skins are sometimes used commercially.

US Migratory Bird Act: protected

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

Accidental visitor.

Rounded Global Status Rank: G5 - Secure

Reasons: Not globally threatened; still numerous though may be declining locally (Hoyo et al. 1992).

No official conservation status.

Global Short Term Trend: Relatively stable to decline of 30%

Comments: Limited trend data are available; however, at least local declines are evident. Surveys during the Alaska-Yukon Waterfowl Breeding Population Survey, 1971-1993, showed a 53 percent decline (Groves et al. 1996). Christmas Bird Count data indicate a non-significant survey-wide decline (-1.4 percent annual change; n = 376), 1959-1988 (Sauer et al. 1996). Survey methods may not be adequate, however, to monitor birds such as this species. Data from Europe suggest a large local decline in southwest Sweden; number of breeding sites has been reduced by 50 percent during the last 40-50 years (Eriksson 1994). In the Shetland Islands, abundance declined by one-third since 1983. In the Orkneys, population are apparently stable (Gibbons et al. 1997).

Global Long Term Trend: Relatively stable to decline of 50%

Degree of Threat: Low

Comments: PREDATION: Predation is major cause of nesting failure (Eberl and Picman 1993). Predators include arctic fox, wolf, glaucous gull, jaegers, snowy owl, and probably other carnivores and raptors.

FLOODING: Flooding of nests and desiccation of ponds leading to stranding, abandonment, or predation may be minor factors of nesting failure (Eberl and Picman 1993).

CONTAMINATION: Given the fish diet, this species may be susceptible to mercury contamination in areas with acidified lakes. Eggs in Sweden, for example, revealed extremely high mercury levels (6.2-14.2 parts per million, dry weight). Residues of chlorinated hydrocarbons and heavy metals also found in tissue samples of birds found dead in Germany, 1980 to 1984 (Heidmann et al. 1988). Red-throated loon also may suffer from decline in food (fish) abundance due to lake acidification in some areas (Eriksson 1994).

HUMAN DISTURBANCE: Substantial numbers may drown as a result of entanglement in fishing nets in winter range (see Johnsgard 1987). As many as 73 percent of nests suffered from human-related disturbance on Igloolik Island, Northwest Territories (Forbes et al. 1992). Red-throated loons are sensitive to human intrusion and may abandon disturbed breeding lakes (Forbes et al. 1992, Hoyo et al. 1992).

Additional hazards include lake eutrophication, water level fluctuations (McIntyre 1994), and oil spills, especially near foraging areas. At least 201 birds found oiled in coastal Britain in 1970s (Hoyo et al. 1992).

Major Threats

Global Protection: Very many (>40) occurrences appropriately protected and managed

Comments: Many occurrences are in protected areas or in area that provide effective protection due to their remoteness.

Red-throated diver skins are sometimes used to make ceremonial dresses.