Gavia arctica

Arctic Ocean, Belgian Exclusive Economic Zone, European waters (ERMS scope), Mediterranean Sea, Polish Exclusive Economic Zone, Portuguese Exclusive Economic Zone, Spanish Exclusive Economic Zone, Swedish Exclusive Economic Zone, United Kingdom Exclusive Economic Zone, Wimereux

This species has a wide range across northern latitudes, breeding on large, deep freshwater lakes in Russia, Scandinavia, Alaska (USA) and Canada. After breeding inviduals move southwards and towards the sea, wintering in sheltered coasts in the north-east Atlantic, and on the eastern and western coasts of the Pacific¹.

Arctic Loons or black-throated divers (Gavia arctica) have a large global distribution, as they are found across roughly 10 million square kilometers. They are a migratory species, restricted to regions throughout the northern hemisphere.

The winter range of Arctic loons is much more extensive than that of their breeding range. In winter, they are primarily found on large lakes off the coasts of Europe, Asia and North America, including the northern tundra and taiga habitats of Canada, Russia, Scandinavia and Greenland. European populations typically inhabit areas ranging from the Baltic Sea to the northern Mediterranean during winter months. North American populations commonly settle along the Pacific coast from the Gulf of Alaska to Baja California during the winter. Throughout the breeding season, Arctic loons extend across portions of Eurasia, and occasionally extend to parts of western Alaska. Roughly half of the western European population breeds in Sweden. Vagrant or accidental individuals also have been noted in northern Africa, southwestern Europe, western Middle East, and India.

Biogeographic Regions: palearctic (Native )

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

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Breeding

Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) BREEDS: Northern Eurasia and western Alaska in Cape Prince of Wales region. WINTERS: Old World and casually along the west coast of North America from western and southern Alaska south to British Columbia (also recorded a few times in California).

Arctic loons grow to an average of 40 to 81 cm in body length. These birds have wing lengths ranging between 114 and 124 cm and have a mean body weight fluctuating between 3 and 5 g. In breeding plumage, they feature white-spotted, black backs segmented into white lines, which are visible above the water while swimming. The head and posterior half of the neck are gray. The front half of the neck has a bold black stripe with long, thin vertical white stripes along both sides of the throat. Commonly referred to as “black-throated loons” which was coined by the black stripe on the throat. During the non-breeding season, the crown and nape darken to black, as does the back which loses the white barring. The face, throat and breast become starkly white and unmarked. This species closely resembles Pacific loons (Gavia pacifica) but may be distinguished by an extensive white flank patch that is present in both breeding and winter plumages.

Female and male Arctic loons are similar in their physical appearances and feature distinctive, deep-red eyes.

Juveniles closely resemble wintering adults, but are a more dusky-gray versus black and may exhibit a faint scaled pattern on their backs and wings.

Range mass: 3 to 5 g.

Range length: 40 to 81 cm.

Range wingspan: 114 to 124 cm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: sexes alike

Length: 66 cm

Weight: 1659 grams

G. ARCTICA has more white on the flanks at the waterline than does G. PACIFICA (see McCaskie et al. 1990, Roberson 1989, and Schulenberg 1989 for further details). See Stallcup (1994) for information on identification of North American loons.

Habitat and Ecology

Systems

• Terrestrial
• Freshwater
• Marine

Arctic loons breed on deep, productive, freshwater lakes or extensive pools with neighboring islands, peninsulas and other humanly-inaccessible nesting sites. They prefer a habitat free of disturbance. Gavia arctica relies on its freshwater breeding territory to provide food. They dive deep in the water for fish and also feed their offspring small fishes and insects until they increase in size, enabling them to feed on larger fish. Outside of the breeding season the species is commonly located among inshore waters along sheltered coasts. Gavia arctica is also occasionally found throughout large inland bodies of freshwater such as natural lakes or streams, and large rivers.

Arctic loons build their nest in May and June, and take about a week to complete. A nest contains piles of aquatic vegetation close to the edge of the water body, usually near a sheltered bay, island, or adjacent river system.

Habitat Regions: temperate ; polar ; freshwater

Terrestrial Biomes: tundra

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

Other Habitat Features: riparian

Depth range based on 247 specimens in 1 taxon.
Water temperature and chemistry ranges based on 75 samples.

Environmental ranges
  Depth range (m): 0 - 0
  Temperature range (°C): 3.078 - 16.316
  Nitrate (umol/L): 0.240 - 7.309
  Salinity (PPS): 6.428 - 35.409
  Oxygen (ml/l): 5.685 - 7.967
  Phosphate (umol/l): 0.273 - 1.033
  Silicate (umol/l): 1.436 - 9.916

Graphical representation

Temperature range (°C): 3.078 - 16.316

Nitrate (umol/L): 0.240 - 7.309

Salinity (PPS): 6.428 - 35.409

Oxygen (ml/l): 5.685 - 7.967

Phosphate (umol/l): 0.273 - 1.033

Silicate (umol/l): 1.436 - 9.916
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

Comments: Nonbreeding: primarily seacoasts, bays, and estuaries, less frequently on lake and rivers (AOU 1983). Nests on tundra and taiga 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.

Gavia arctica are carnivores. They are primarily piscivorous, as their diet relies heavily upon fish, but also crustaceans and aquatic insects. They dive deep from the surface to feed. When a fish or other type of prey is caught, the loon throws back its head and swallows it. Newly hatched young are fed by their parents. Their diets consist predominantly of aquatic insects, with an increasing proportion of fish in their diet as they grow larger. In lakes with low densities of fish, young often are fed almost entirely on aquatic insects.

Animal Foods: fish; insects; aquatic crustaceans

Primary Diet: carnivore (Piscivore )

Arctic loons serve as both prey and predator within their ecosystems. They provide food for local predators as well as control populations of fish, crustaceans and aquatic insects. They are also a host to several different body parasites, most of which are tapeworms and flukes.

Commensal/Parasitic Species:

• tapeworms (class Cestoda)
• flukes (class Trematoda)

Arctic loon adults do not have many natural predators. Bald eagles are their main predators. Bald eagles attack unsuspecting, incubating parents. Young chicks also are vulnerable to predation by large predatory fish, bald eagles and herring gulls.

There are a number of other animals who primarily prey on eggs. Common egg predators include raccoons, gulls, crows and foxes. Predation on eggs of arctic loons takes place when an incubating adult is forced off the nest because of human disturbance, or if it is preoccupied by an intruder. During this time the unattended eggs quickly attract nearby predators.

Adult Arctic loons respond to the sight of a predator with wailing and alarming vocalizations to inform both offspring and mates of the intruder. The young chicks respond by quickly swimming to a protected area of shoreline and remain hidden until the threat is no longer present. On freshwater lakes, adults are generally safe from underwater predators, but young chicks are vulnerable to large predatory fish. If an adult spots an underwater predator they will tread water rapidly with their feet and flap wings to discourage them from advancing any closer.

Known Predators:

• bald eagles (Haliaeetus leucocephalus)
• herring gulls (Larus argentatus)
• raccoons (Procyon)
• gulls (Laridae)
• crows (Corvus)
• foxes (Canidae)

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

Estimated Number of Occurrences: 81 to >300

10,000 - 1,000,000 individuals

Arctic loons produce a variety of calls. A low call, which is very weak and sounds much like a human humming, is performed by both female and male. Moaning occurs as a low call with a strong sound, produced by both sexes as early as two months of age. Yodeling, a "kuik-kukuik-kukuik” sound, is the strongest vocalization produced by the species, which is performed only by the male. Even in unfavorable conditions this call can be heard up to distances surpassing 10 km. Both low calls and moaning vocalizations are recognized as contact calls. The difference being, a low call is a normal contact call, moaning is a high intensity contact call. Yodeling is a territorial call made by the male loon preparing to defend his territory. Territorial calls are often paired with threatening behaviors such as circling or bill dipping to warn of an imminent attack.

Like most birds, Arctic loons perceive their environments through visual, auditory, tactile and chemical stimuli.

Communication Channels: visual ; tactile ; acoustic

Arctic loons are thought to be relatively long-lived birds. However, there is little information available directly pertaining to their lifespan. The oldest recorded wild Arctic loon lived to be 28 years old.

Range lifespan
Status: wild: 28 (high) years.

Maximum longevity: 28 years (wild)

Arctic loons are monogamous, meaning they live their whole lives with only one mate. The couple stays together during their winter migration and on their wintering grounds. New couples use a number of synchronous movements including bill-dipping, splash diving and rushing under water. Mating occurs on the water banks and often occurs right after the birds have arrived in the breeding area. This species exhibits strong site fidelity and often uses the same nesting site for every breeding season. Gavia arctica will continue to use this site for a short time following mating.

Mating System: monogamous

Arctic loons occupying southern regions begin their breeding season in May, whereas the breeding season in northern regions is determined by the onset of spring. In the spring they migrate from their wintering grounds. Upon nest completion the female will lay 1 to 3 eggs. The eggs are normally olive-brown with dark brown spots. Incubation takes 27 to 29 days followed by a vital growth period of 9 to 10 weeks. When the young are about two months old, they gain the ability to fly or "fledge". They reach sexual maturity in 2 to 3 years.

Breeding interval: Arctic loons breed once a year

Breeding season: The breeding season varies geographically but occurs in spring

Range eggs per season: 2 to 3.

Range time to hatching: 27 to 29 days.

Average fledging age: 2 months.

Range time to independence: 2 to 3 months.

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)

The male loon is responsible for building the nest. Both parents take part in the incubation, but the females display a higher percentage of parental care. Incubation takes about 27 to 29 days followed by a vital growth period of 9 to 10 weeks, where both parents aid in rearing the offspring. The semiprecocial young spend the first day in the nest, but are able to swim at 2 to 4 days old. Both parents participate in feeding the young constantly throughout the first few weeks. Parents individually feed offspring one at a time, offering only one piece of food at a time, consisting usually of crustaceans. Newly hatched young often ride on their parents' backs, likely to avoid predators and conserve energy. At several weeks of age, the young start feeding themselves, but are still sometimes fed by their parents. When they are about two months old, they can fly and are considered fledgelings. They reach sexual maturity in 2 to 3 years.

Parental Investment: precocial ; male parental care ; female parental care ; pre-fertilization (Provisioning, Protecting: Male, Female); pre-hatching/birth (Provisioning: Male, Female, Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Female, Protecting: Male, Female)

Presumably similar to G. PACIFICA.

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 6
Specimens with Barcodes: 6
Species With Barcodes: 1

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

There are 6 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.

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Year Assessed

Assessor/s

Reviewer/s

Contributor/s

Justification

History

• 2008
  Least Concern
• 2004
  Least Concern

Arctic loons are vulnerable to human disturbances within their breeding sites. Changes in the habitat, including alterations of water levels, acidification of water as well as oil and heavy metal pollution are constant threats for this species. Current populations tend to be fairly large but are progressively decline throughout the southern part of their range. According to the assessment of the International Union for Conservation of Nature and Natural Resources (IUCN), Arctic loons are categorized as a species of least concern. The European breeding population of Arctic loons is relatively small (less than 92,000 pairs), and underwent a large decline between 1970 and 1990. On the other hand, Arctic loon populations in Sweden and Finland were stable and increased between 1990 and 2000.

US Migratory Bird Act: protected

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: least concern

United States

Rounded National Status Rank: N1B - Critically Imperiled

Rounded Global Status Rank: G5 - Secure

Global Short Term Trend: Unknown

Global Long Term Trend: Unknown

Major Threats

Arctic loons feed primarily on fish and may be considered competitors for fishermen.

Inuit, a member of the Eskimo peoples inhabiting northernmost North America from northern Alaska to eastern Canada, use Arctic loons' eggs for food. They sometimes hunt loons on the breeding ground for consumption as well.