Uria lomvia

Geographic Range

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 nearctic
  • native native
• palearctic palearctic
  • native native
• arctic ocean arctic ocean
  • native native
• atlantic ocean atlantic ocean
  • native native
• pacific ocean pacific ocean
  • native native

• Other Geographic Terms
• holarctic holarctic

Habitat

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.

• Habitat Regions
• polar polar
• terrestrial terrestrial
• saltwater or marine saltwater or marine

• Terrestrial Biomes
• tundra tundra
• icecap

• Aquatic Biomes
• pelagic pelagic
• coastal coastal

Physical Description

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.

• Other Physical Features
• endothermic endothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• sexes alike

Reproduction

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 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).

• Key Reproductive Features
• iteroparous iteroparous
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• oviparous 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 precocial
• male parental care male parental care
• female 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

Lifespan/Longevity

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.

Behavior

Thick-billed murres form large, dense aggregations in colonies on cliff ledges where breeding occurs. These birds are primarily aquatic and they forage for food at depths greater than 100 meters, in pursuit of fish, squid and crustaceans . They are also characterized by flight, although due to their awkward takeoffs, they are far better swimmers. Adult and juvenile thick-billed murres swim large distances in migratory journeys away from their breeding colonies, towards their rearing and wintering area. Upon fledging, chicks swim nearly 1,000 kilometers (620 miles) accompanied by their male parent in the first leg of the journey to their wintering grounds. During this time, adults molt into their winter plumage and temporarily lose their ability to fly until the reemergence of their flight feathers. Uria lomvia is generally active during the day.

• Key Behaviors
• terricolous
• flies
• natatorial natatorial
• diurnal diurnal
• motile motile
• migratory migratory
• social social
• colonial colonial

Home Range

Thick-billed murres travel 10 to 168 km one-way to foraging sites. Foraging patterns of a population of thick-billed murres breeding in northwestern Iceland were tracked using bird-borne data loggers.

Communication and Perception

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 acoustic

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

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.

• Primary Diet
• carnivore carnivore
  • piscivore piscivore
  • molluscivore molluscivore
  • eats other marine invertebrates
• planktivore planktivore

• Animal Foods
• fish
• mollusks
• aquatic or marine worms
• aquatic crustaceans
• other marine invertebrates
• zooplankton zooplankton

• Foraging Behavior
• stores or caches food stores or caches food

Predation

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.

Ecosystem Roles

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.

Economic Importance for Humans: Positive

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 food
• research and education

Economic Importance for Humans: Negative

There are no known adverse affects of U. lomvia on humans.

Conservation Status

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 .

Other Comments

This species is named after Morten Thrane Brünnich, a Danish zoologist.

Additional Links

Encyclopedia of Life

BioKIDS Critter Catalog

Contributors

Roselyn Thalathara (author), The College of New Jersey, Matthew Wund (editor), The College of New Jersey, Leila Siciliano Martina (editor), Texas State University.

References

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Birkhead, T., S. Johnson, D. Nettleship. 1985. Extra-pair matings and mate guarding in the common murre Uria aalge . Animal Behavior , 33/2: 608-619. Accessed November 15, 2012 at http://www.sciencedirect.com/science/article/pii/S0003347285800853 .

Bradstreet, M. 1980. Thick-billed murres and black guillemots in the Barrow Strait area, N.W.T., during spring: diets and food availability along ice edges. Canadian Journal of Zoology , 58/11: 2120-2140. Accessed October 13, 2012 at http://www.nrcresearchpress.com/doi/abs/10.1139/z80-292#citart1 .

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