Thick-billed murres are carnivorous and have been known to consume a variety of marine species, including pollock, sculpin, flounder, capelin, sand eel, Atka mackerel, squid, Arctic cod, annelid worms, crustaceans, and large zooplankton. Uria lomvia forage underwater at depths greater than 100 meters, in waters less than 8 degrees Celsius.
The foraging behavior of U. lomvia varies based on the type of prey and habitat. They usually return to the colony with a single prey item, except when capturing invertebrates. As generalist marine predators, prey-capture strategies of U. lomvia are based on the potential energy gain from a prey item, as well as the energy expenditure required to capture the prey. Thick-billed murres capture pelagic prey items in active pursuit; they seek and pursue schooling mid-water prey. On the other hand, murres spend a greater deal of time, but less energy, searching for benthic prey, gliding slowly along the bottom searching in the sediments or rocks. Furthermore, based on its location, U. lomvia may also have habitat-related differences in diet. At offshore ice edges, they feed in the water column and at the undersurface of the landfast ice. In contrast, at coastal ice edges, U. lomvia feed at the ice undersurface, on the sea bottom, and in the water column.
Animal Foods: fish; mollusks; aquatic or marine worms; aquatic crustaceans; other marine invertebrates; zooplankton
Foraging Behavior: stores or caches food
Primary Diet: carnivore (Piscivore , Molluscivore , Eats other marine invertebrates); planktivore
Thick-billed murres are mainly vulnerable to aerial predators including common ravens, eagles, and particularly gulls. Glaucous gulls are known to prey particularly upon murre eggs and chicks when left unattended. However, the dense nesting colony of U. lomvia, in which the birds stand side-by-side in tight-packed aggregations, help protect adults and their young from aerial predation, as well as terrestrial predation, particularly from arctic foxes.
In addition, humans, including groups in Canada and Alaska, hunt and consume murre eggs for food.
Known Predators:
Thick-billed murres are stout seabirds with black feathers covering their head, back, and wings. White feathers cover their breast and underside. During winter, their neck and face become a paler grey. Their spear-shaped bills are grey-black with a white line running along the sides of the upper mandible of the bill. Thick-billed murres can be distinguished from common murres (Uria aalge) by their relatively robust features, which include a heavier head and neck and a short, stout bill. Their back also appears blacker than common murres, while also lacking most of the brown streaking on the flanks identified in common murres. Thick-billed murres are diving birds and have webbed-feet, with short legs and wings. Because their feet are set far back on their body, they have a distinct upright posture, closely resembling the stance of a penguin. Male and female thick-billed murres appear similar. Juveniles resemble adults in terms of plumage, but have a smaller, more slender bill.
Range mass: 750 to 1481 g.
Average length: 45 cm.
Average wingspan: 71 cm.
Sexual Dimorphism: sexes alike
Other Physical Features: endothermic ; bilateral symmetry
The average lifespan of Uria lomvia in the wild can be up to 25 years, with female birds reaching reproductive maturity at 5 to 6 years of age. In northeastern Canada, annual adult survival was estimated at 91%, while that of young from departure to three years of age was estimated at 52%. Thick-billed murres are vulnerable to anthropogenic threats, such as oil spills and gill-netting. In some regions, they are hunted for food by communities in Alaska and Canada.
Range lifespan
Status: wild: 29 (high) years.
Typical lifespan
Status: wild: 25 (high) years.
Thick-billed murres are marine birds and remain along sea coasts as far offshore as the continental shelf edge. This species is most often found in large flocks out to sea in the open ocean during winter, but vagrants blown inland may appear in bays, estuaries, or reservoirs. They are generally a mid-water feeder; although, they are also notable as one of the deepest underwater divers, reaching depths of more than 100 meters (330 feet) in pursuit of prey. Uria lomvia can also fly at speeds of 75 mph once it is airborne, although it swims far better than it flies given its awkward takeoff. Thick-billed murres also form large aggregations on rocky coasts where the female normally lays her egg on a narrow ledge along a steep sea cliff; rarely, they are found in caves and crevices. Murres are found in greater numbers on islands rather than on mainland coasts.
Range elevation: 0 (low) m.
Average depth: greater than 100 m.
Habitat Regions: polar ; terrestrial ; saltwater or marine
Terrestrial Biomes: tundra ; icecap
Aquatic Biomes: pelagic ; coastal
Uria lomvia (thick-billed murres or Brunnich's guillemots) has a circumpolar distribution, found entirely within Arctic and sub-Arctic waters. This migratory waterbird has a broad geographic breeding distribution in the summer, located as far south as the rocky coasts of Alaska, Newfoundland, Labrador, Greenland, Scandinavia, and the Kuril Islands in Russia. During winter, thick-billed murres move to open water, usually staying within the marginal ice zone. Wintering distributions of U. lomvia range from off the edge of open ice, southward to Nova Scotia and northern British Columbia. During the winter, they are found off the coasts of Greenland, northern Europe, the Mid-Atlantic, the Pacific Northwest of the United States, and southward in the Pacific Ocean to central Japan. After large storms, some thick-billed murres appear as vagrants further south or inland from their typical winter range.
Biogeographic Regions: nearctic (Native ); palearctic (Native ); arctic ocean (Native ); atlantic ocean (Native ); pacific ocean (Native )
Other Geographic Terms: holarctic
Thick-billed murres are predators to various fish, as well as other marine organisms discussed above. They are also prey for common ravens, eagles, gulls, and arctic foxes. In addition, marine parasites, including species of parasitic nematodes, can be introduced into the intestines of murres through the consumption of infected fish.
These seabirds also play a significant role in marine ecosystems, based on their pelagic foraging patterns. Uria lomvia actively track the spatial distribution of mobile prey, such as capelin at several scales, reflecting the hierarchal properties of the prey system. The distribution of mobile prey have varying effects on predator-prey interactions, as small pelagic schooling fish and crustaceans can form high density patches of schools and swarms as an anti-predator response. Consequently, U. lomvia search for large-scale patches by using long travel distances and low turning frequency. At this point, they start searching for smaller scale patches using shorter travel distances and higher turning frequencies to minimize the search area. Such a search pattern should reflect the fractal properties of the prey system.
Commensal/Parasitic Species:
Towards the Arctic region, thick-billed murres are often hunted as a food source. Canadian natives shoot the birds near their breeding colonies or during their migration from the coast of Greenland each year in a traditional food hunt. In addition, certain groups, such as Alaskan natives, collect murre eggs for food. In the 1990s, an average household on St. Lawrence Island (located west of mainland Alaska in the Bering Sea) consumed 60 to 104 murre eggs annually.
Because they nest in such large colonies, thick-billed murres are an indicator species for researchers. Changes in the availability of food or environmental pollution, for example, can result in large numbers of dead murres washing ashore.
Positive Impacts: food ; research and education
There are no known adverse affects of U. lomvia on humans.
As one of the most numerous seabirds in the northern hemisphere, the global population of thick-billed murres is healthy and is estimated to number greater than 22,000,000 individuals, over a large range. Therefore, this species does not approach the thresholds for a vulnerable species. However, threats remain, especially from oil spills and gill-netting, as well as an increasing numbers of natural predators, such as gulls.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
Thick-billed murres are believed to communicate vocally. Among murre chicks, calls are mainly flute-like sounds, characterized by a rapidly frequency-modulated departure call. Such a call is given shortly before, during, and after they leave the colony as fledglings, as a mode of communication between the chick and the male parent in attendance. Adult calls, in contrast, are lower pitched and sound gruffer. Based on the closely related common murre, the calls are heavy, resembling a laughing “ha ha ha” sound, or a more prolonged, growling sound. In aggressive behaviors, common murres emit a weak, rhythmic vocalization. There is individual variation in adult crow calls based on pitch, duration, and number of syllables. Such variation indicates the potential for individual recognition among U. lomvia through temporal features, especially recognition of the calls of parents by their chicks.
Although information about perception in U. lomvia remains sparse, aquatic birds in general have multiple mechanisms to compensate for the refractive loss of the cornea underwater. Suggested mechanisms include an exaggerated accommodative increase in refractive power underwater, the development of a flattened cornea non-refractive in both air and water, and nictitating membranes that act as refractive goggles underwater.
Communication Channels: acoustic
Perception Channels: visual ; tactile ; acoustic ; chemical
This species is named after Morten Thrane Brünnich, a Danish zoologist.
Although there is little information on the mating systems of Uria lomvia, forced extra-pair copulations (FEPC) and mate guarding have been observed frequently in the closely related common murre. Within the domains of their densely packed colony structure, social monogamy is common. Males are present continuously in the colony before the eggs are laid, while females are present infrequently. With a greater number of males present, the number of extra-pair copulations increases. Such forced copulations occur when the mates of females are absent. Generally, females make attempts to resist such advances, while males vigorously defend their mates from other males. FEPCs committed by males vary from 0 to 32 per season.
Mating System: monogamous
Thick-billed murres begin breeding between five to six years of age and nest in large dense noisy colonies on narrow cliff ledges. Within their colony, the birds stand side by side, forming a tight-knit nesting habitat to protect themselves and their chicks from aerial predators. Uria lomvia typically arrive at nesting sites in the spring, from April to May, but because ledges are often still covered in snow, egg laying does not begin until the end of May or early June, depending on sea temperatures. Females lay their eggs at approximately the same time in order to synchronize the time of hatching and the point at which juveniles jump off breeding ledges into the sea, to undertake their long migration to wintering grounds. Female thick-billed murres lay a single egg with a thick-heavy shell, often greenish to pinkish in hue, with patterns of mottling designed for life on the edge; the pear-shaped egg does not roll when jostled. Females do not build nests but arrange pebbles along with other debris close to the egg, while securing the egg in place with feces to prevent the egg from rolling off the ledge. Both males and females take shifts incubating the egg with their weight directly on the egg, over the course of an average 33-day period. The egg hatches in 30 to 35 days, with both parents involved in the care of the chick until it fledges at about 21-days-old.
Thick-billed murres employ a life-history strategy typical for marine birds, characterized by several years of deferred breeding and a single-egg clutch. Egg sizes increases with female age, and the date the egg is laid advances over her first few breeding attempts. However, only about 20 to 30% of females re-lay after they lose their egg, mainly because females that lose their eggs tend to be young and inexperienced. In addition, there is a 5 to 6% average reduction in the size of a female’s replacement egg, compared to her first egg. Uria lomvia have a largely precocial post-hatching development, displaying many characteristics of a precocial species (e.g. relatively large yolks).
Breeding interval: Thick-billed murres typically breed once yearly.
Breeding season: Thick-billed murres breed at the end of May to early July.
Average eggs per season: 1.
Average time to hatching: 30 to 35 days.
Average fledging age: 21 days.
Range time to independence: 4 to 8 weeks.
Average age at sexual or reproductive maturity (female): 5 to 6 years.
Average age at sexual or reproductive maturity (male): 5 to 6 years.
Key Reproductive Features: iteroparous ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous
Both males and females have great parental investment in their single-egg clutch. Both incubate the egg constantly, taking shifts of 12 to 24 hours over a 33-day period, after which, it hatches. The nestling is then fed, mainly fish, by both parents at the breeding site for approximately 15 to 30 days. Usually, it fledges at about 21-days-old. After that point, the female departs for sea. The male parent stays on to care for the chick for a longer period of time, after which, he departs for sea with the chick at night during calm weather. Males spend 4 to 8 weeks with the chick before it reaches independence.
Parental Investment: precocial ; male parental care ; female parental care ; pre-hatching/birth (Provisioning: Male, Female, Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Protecting: Male)
A medium-sized (17-19 inches) auk, the Thick-billed Murre in summer is most easily identified by its black back and head, white breast, and black spear-shaped bill with a thick white stripe along both sides. During the winter, this species becomes paler gray on the neck and face. This species may be separated from the related Common Murre (Uria aalge) by that species’ thinner all-black bill and from the Razorbill (Alca torda) by that species’ much thicker bill. Male and female Razorbills are similar to one another in all seasons. The Thick-billed Murre breeds along the coasts of Alaska, northern Canada, northern Europe, and Siberia. This species spends the winter at sea, extending south from its breeding range as far as the Mid-Atlantic region, the Pacific Northwest, Britain, and northern Japan. Individuals may appear further south or inland from this species’ typical winter range after large storms. Thick-billed Murres breed in large seabird colonies on cliffs on islands or along rocky northern coasts. During the winter, this species is usually seen far out to sea on the open ocean, although vagrants blown inland may appear on other large bodies of water, such as bays, estuaries, or reservoirs. Thick-billed Murres primarily eat small fish. During the breeding season, birdwatchers have found that Thick-billed Murres are most easily observed from boats at the base of large seabird colonies. During the winter, this species may be observed from ships far out to sea or, if from shore, only during large storms with the use of high-power optics. Thick-billed Murres are mainly active during the day.
A medium-sized (17-19 inches) auk, the Thick-billed Murre in summer is most easily identified by its black back and head, white breast, and black spear-shaped bill with a thick white stripe along both sides. During the winter, this species becomes paler gray on the neck and face. This species may be separated from the related Common Murre (Uria aalge) by that species’ thinner all-black bill and from the Razorbill (Alca torda) by that species’ much thicker bill. Male and female Razorbills are similar to one another in all seasons. The Thick-billed Murre breeds along the coasts of Alaska, northern Canada, northern Europe, and Siberia. This species spends the winter at sea, extending south from its breeding range as far as the Mid-Atlantic region, the Pacific Northwest, Britain, and northern Japan. Individuals may appear further south or inland from this species’ typical winter range after large storms. Thick-billed Murres breed in large seabird colonies on cliffs on islands or along rocky northern coasts. During the winter, this species is usually seen far out to sea on the open ocean, although vagrants blown inland may appear on other large bodies of water, such as bays, estuaries, or reservoirs. Thick-billed Murres primarily eat small fish. During the breeding season, birdwatchers have found that Thick-billed Murres are most easily observed from boats at the base of large seabird colonies. During the winter, this species may be observed from ships far out to sea or, if from shore, only during large storms with the use of high-power optics. Thick-billed Murres are mainly active during the day.
The thick-billed murre or Brünnich's guillemot (Uria lomvia) is a bird in the auk family (Alcidae). This bird is named after the Danish zoologist Morten Thrane Brünnich. The very deeply black North Pacific subspecies Uria lomvia arra is also called Pallas' murre after its describer. The genus name is from Ancient Greek ouria, a waterbird mentioned by Athenaeus. The species term lomvia is a Swedish word for an auk or diver.[2] The English "guillemot" is from French guillemot probably derived from Guillaume, "William".[3] "Murre" is of uncertain origins, but may imitate the call of the common guillemot.[4]
Murres have the highest flight cost, for their body size, of any animal.[5]
Since the extinction of the great auk in the mid-19th century, the murres are the largest living members of the Alcidae.[6] The thick-billed murre and the closely related common guillemot (or common murre, U. aalge) are similarly sized, but the thick-billed still bests the other species in both average and maximum size. The thick-billed murre measures 40–48 cm (16–19 in) in total length, spans 64–81 cm (25–32 in) across the wings and weighs 736–1,481 g (26.0–52.2 oz).[7][8][9] The Pacific race (U. l. arra) is larger than the Atlantic race, especially in bill dimensions.[10]
Adult birds are black on the head, neck, back and wings with white underparts. The bill is long and pointed. They have a small rounded black tail. The lower face becomes white in winter. This species produces a variety of harsh cackling calls at the breeding colonies, but is silent at sea.
They differ from the common murre in their thicker, shorter bill with white gape stripe and their darker head and back; the "bridled" morph is unknown in U. lomvia - a murre has either a white eye-stripe, or a white bill-stripe, or neither, but never both; it may be that this is character displacement, enabling individual birds to recognize conspecifics at a distance in the densely packed breeding colonies as the bridled morph is most common by far in North Atlantic colonies where both species of guillemots breed. In winter, there is less white on the thick-billed murre's face. They look shorter than the common murre in flight. First year birds have smaller bills than adults and the white line on the bill is often obscure, making the bill an unreliable way to identify them at this age. The head pattern is the best way to distinguish first-year birds from common murres.[11]
The thick-billed murre is distributed across the polar and sub-polar regions of the Northern Hemisphere where four subspecies exist; one lives on the Atlantic and Arctic oceans of North America (U. l. lomvia), another on the Pacific coast of North America (U. l. arra), and two others that inhabit the Russian arctic (U.l.eleonorae and U.heckeri).[12][13]
Thick-billed murres spend all of their lives at sea in waters which remain below 8°C,[12] except during the breeding season where they form dense colonies on cliffs.[12][13]
Thick-billed murres form vast breeding colonies, sometimes composed of over a million breeding birds, on narrow ledges and steep cliffs which face the water.[13] They have the smallest territory of any bird,[13] requiring less than one square foot per individual.[12] A breeding pair will lay a single egg each year.[12][14] Despite this, they are one of the most abundant marine birds in the Northern Hemisphere.[13]
Adults perform communal displays early in the breeding season to time their breeding cycles.[12] They do not build nests, but lay the egg directly on bare rock.[12] Both parents are involved in incubating the egg and raising the young.[15][16] Due to the enormous amount of energy needed to take off in flight, adults can only provide one food item at a time to their chick.[13] Chicks spend between 18 and 25 days on the cliffs before leaving for the sea.[12][13] Once ready to leave, the young will await nightfall and jump off the edge towards the water.[13] A parent immediately jumps after and glides within centimeters of the fledgling.[15] At sea, the male and the chick stay together for around 8 weeks during which the adult continues to provide food for the young.[13]
Survival rates of the young is not based on the number of individuals in the colony, but rather on the age of the breeders within the colony.[12] Offspring of inexperienced pairs grow more slowly than those of experienced breeders, possibly because they do not receive as much food from their parents.[14] Also, pairs which contain at least one young breeding bird tend to have lower hatch rates.[17] Older and experienced adults obtain the better nesting sites located in the center of the colony, while the inexperienced individuals are kept on the margins[12] where their young are more likely to be preyed upon.[18]
They move south in winter into northernmost areas of the north Atlantic and Pacific, but only to keep in ice-free waters.
The thick-billed murre's flight is strong and direct, and they have fast wing beats due to the short wings. Like the other auks, these birds forage for food by using their wings to 'swim' underwater.[12] They are accomplished divers, reaching depths of up to 150 m and diving for up to four minutes at a time; usually however birds make either shallow short dives or dive down to 21–40 m for longer periods.[19] While hunting, the diving trajectory resembles a flattened 'U'.[19] Birds will make long trips to get to favorite feeding grounds; while they usually forage several dozen km from their nest sites, they often travel more than 100 km to fish.[20][6] The strong and direct flight of murres, which is, for their body size, the most costly form of sustained locomotion of any animal, is a result of their short wingspan[5]
The diving depths and durations regularly achieved by these birds indicate that they, and similar auks, have some—as yet unknown—mechanism to avoid diving sickness and lung collapse when surfacing.[19] It is postulated that auks temporarily absorb excess gases into the vascular structure of their bones. From there, it is gradually released from temporary storage in a controlled process of decompression.
The nominate race feeds primarily on fish such as Gadus spp. and Arctic cod (Boreogadus saida),[12] as well as the pelagic amphipod Parathemisto libellula.[13] Other fish such as capelin (Mallotus villosus) and Myoxocephalus spp., as well as other crustaceans, polychaetes, and a few molluscs, are found in their diet but in relatively low numbers.[12] When wintering near Newfoundland, capelin can account for over 90 percent of their diet.[12]
Thick-billed murres have few natural predators because the immense number of concentrated birds found on the breeding colonies and the inaccessibility of these breeding sites make it extremely difficult for them to be preyed upon.[12] Their main predator is the glaucous gull (Larus hyperboreus), and these feed exclusively on eggs and chicks.[15][18] The common raven (Corvus corax) may also try to obtain eggs and hatchlings when they are left unattended.[12][21]
Although declines have been observed in many parts of their range,[12] the thick-billed murre is not a species of concern as the total population is estimated to contain between 15 and 20 million individuals worldwide.[13]
Egg harvesting and hunting of adult birds are major threats in Greenland, where populations fell steeply between the 1960s and 1980s.[22] In the Barents Sea region, the species has declined locally, due to influences associated with polar stations in Russia. Fisheries may also be a threat, but because thick-billed murres are better able to use alternative food sources the effect of over-fishing is not as severe as on the common murre. Pollution from oil at sea exerts another major threat. Murres are among the seabirds most sensitive to oil contamination.[23] Incidental mortality brought on by entanglement with fishing gear is also an important cause of population decline.[24]
Thick-billed murres are closely associated with sea-ice throughout the year.[13] Consequently, some scientists believe that climate change may be a threat to this Arctic-breeding species.[25] However the species seems adaptable. Populations at the southern edge of their range switched from feeding on ice-associated Arctic cod to warmer-water capelin[26] as ice break-up became earlier. Dates for egg-laying advanced with the earlier disappearance of ice. The growth of chicks is slower in years when ice break-up is early relative to egg-laying by the murres. In extremely warm years, mosquitoes and heat kill some breeders.[27]
Brünnich's guillemot is a rare vagrant in European countries south of the breeding range. In Britain, over 30 individuals have been recorded, but over half of these were tideline corpses. Of those that were seen alive, only three have remained long enough to be seen by large numbers of observers. All three were in Shetland - winter individuals in February 1987 and November/December 2005, and a bird in an auk colony in summer 1989. The 1989 and 2005 birds were both found by the same observer, Martin Heubeck.
The species has been recorded once in Ireland,[28] and has also been recorded in the Netherlands. In the western Atlantic, they may range as far as Florida,[29] and in the Pacific to California.[6] Before 1950, large numbers appeared on the North American Great Lakes in early winter, passing up the St. Lawrence River from the East coast. Such irruptions have not been seen since 1952.[30]
The thick-billed murre or Brünnich's guillemot (Uria lomvia) is a bird in the auk family (Alcidae). This bird is named after the Danish zoologist Morten Thrane Brünnich. The very deeply black North Pacific subspecies Uria lomvia arra is also called Pallas' murre after its describer. The genus name is from Ancient Greek ouria, a waterbird mentioned by Athenaeus. The species term lomvia is a Swedish word for an auk or diver. The English "guillemot" is from French guillemot probably derived from Guillaume, "William". "Murre" is of uncertain origins, but may imitate the call of the common guillemot.
Murres have the highest flight cost, for their body size, of any animal.
