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. ("Encyclopedia of Life", 2012; "ICUN Red List", 2012; Gaston, et al., 2011; "National Geographic", 2012)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.
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. ("Encyclopedia of Life", 2012; "National Park Service", 2012; Hallvard, 2012; "National Geographic", 2012)
Although there is little information on the mating systems of 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. (Birkhead, et al., 1985), forced extra-pair copulations (FEPC) and mate guarding have been observed frequently in the closely related
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. ("ICUN Red List", 2012; "National Park Service", 2012; Hallvard, 2012; Herzberg, et al., 2003; Hipfner and Gaston, 1999; "Global Species", 2012; "National Geographic", 2012)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. (Herzberg, et al., 2003)have a largely precocial post-hatching development, displaying many characteristics of a precocial species (e.g. relatively large yolks).
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. ("National Park Service", 2012; Gaston, et al., 2005; Hallvard, 2012; "National Geographic", 2012)
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. is generally active during the day. ("Encyclopedia of Life", 2012; Hallvard, 2012; "National Geographic", 2012)
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. (Benvenuti, et al., 1998)
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 through temporal features, especially recognition of the calls of parents by their chicks. (Hallvard, 2012; Lefevre, et al., 2011)
Although information about perception in (Sivak, 1980)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.
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. forage underwater at depths greater than 100 meters, in waters less than 8 degrees Celsius. ("ICUN Red List", 2012; "National Park Service", 2012; Bradstreet, 1980; "Global Species", 2012)
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 , 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. ("National Park Service", 2012; Hallvard, 2012)
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. ("National Park Service", 2012; Hallvard, 2012; "Global Species", 2012)
These seabirds also play a significant role in marine ecosystems, based on their pelagic foraging patterns. 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, 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. ("National Park Service", 2012; Fauchald, et al., 2000; "Global Species", 2012)actively track the spatial distribution of mobile prey, such as
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. ("National Park Service", 2012; "National Geographic", 2012)
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. ("National Park Service", 2012; "National Geographic", 2012)
There are no known adverse affects ofon 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. ("ICUN Red List", 2012; Hallvard, 2012)
This species is named after Morten Thrane Brünnich, a Danish zoologist. ("Global Species", 2012)
Roselyn Thalathara (author), The College of New Jersey, Matthew Wund (editor), The College of New Jersey, Leila Siciliano Martina (editor), Animal Diversity Web Staff.
the body of water between Europe, Asia, and North America which occurs mostly north of the Arctic circle.
the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.
living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.
uses sound to communicate
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
an animal that mainly eats meat
uses smells or other chemicals to communicate
the nearshore aquatic habitats near a coast, or shoreline.
used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
parental care is carried out by females
A substance that provides both nutrients and energy to a living thing.
a distribution that more or less circles the Arctic, so occurring in both the Nearctic and Palearctic biogeographic regions.
Found in northern North America and northern Europe or Asia.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
parental care is carried out by males
makes seasonal movements between breeding and wintering grounds
eats mollusks, members of Phylum Mollusca
Having one mate at a time.
having the capacity to move from one place to another.
specialized for swimming
the area in which the animal is naturally found, the region in which it is endemic.
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
An aquatic biome consisting of the open ocean, far from land, does not include sea bottom (benthic zone).
an animal that mainly eats fish
an animal that mainly eats plankton
the regions of the earth that surround the north and south poles, from the north pole to 60 degrees north and from the south pole to 60 degrees south.
mainly lives in oceans, seas, or other bodies of salt water.
reproduction that includes combining the genetic contribution of two individuals, a male and a female
associates with others of its species; forms social groups.
places a food item in a special place to be eaten later. Also called "hoarding"
uses touch to communicate
Living on the ground.
A terrestrial biome with low, shrubby or mat-like vegetation found at extremely high latitudes or elevations, near the limit of plant growth. Soils usually subject to permafrost. Plant diversity is typically low and the growing season is short.
uses sight to communicate
young are relatively well-developed when born
animal constituent of plankton; mainly small crustaceans and fish larvae. (Compare to phytoplankton.)
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