Kaira is the largest feathered bird in the auk family. She took this place of honor after the extinction of the species of wingless loons. This is a numerous genus, which has more than 3 million pairs in Russia alone. This is a sea bird, her life is spent on drifting ice and steep cliffs. During the breeding season, bird markets reach several tens of thousands of birds. You can learn a lot of interesting facts about the murre here.
Origin of the species and description
The genus Uria was defined by the French zoologist M. Brisson in 1760 with the establishment of the slender-billed murre (Uria aalge) as the nominal species. The guillemots are related to the auks (Alca torda), little auks (Alle alle), and the extinct great razorbill, and together they make up the auk family (Alcidae). Despite their initial definition, according to DNA studies, they are not as closely related to Cepphus grylle as previously thought.
Interesting fact: The name of the genus comes from the ancient Greek uria, a waterfowl mentioned by Athenaeus.
The genus Uria contains two species: thin-billed murre (U. aalge) and thick-billed murre (U. lomvia)
Some prehistoric species of Uria are also known:
- uria bordkorbi, 1981, Howard – Monterey, Late Miocene Lompoc, USA;
- uria affinis, 1872, Marsh – Late Pleistocene in the USA;
- uria paleohesperis, 1982, Howard – Late Miocene, USA;
- uria onoi Watanabe, 2016, Matsuoka and Hasegawa – mid-late Pleistocene, Japan.
U. brodkorbi is interesting in that it is the only known representative of auks found in the temperate and subtropical Pacific, with the exception of the very margin of the U. aalge range. This suggests that Uria species, which are a related taxon to all other auks and are thought to have evolved similarly in the Atlantic, may have evolved in the Caribbean or close to the Isthmus of Panama. The modern Pacific distribution would then be part of the later Arctic expansion, while most of the other lineages form clades with a continuous range in the Pacific Ocean from arctic to subtropical waters.
Appearance and features
Guillemots are robust seabirds with black feathers covering their head, back and wings. White feathers cover their chest and lower torso and wings. Both types of guillemots have a size of 39 to 49 cm, and a weight of about 1-1.5 kg. After the extinction of the great auk (P. impennis), these birds became the largest representatives of auks. Their wingspan is 61 — 73 cm.
In winter, their neck and face become pale gray. Their spear-shaped beak is grey-black with a white line running along the sides of the upper jaw. Long-billed guillemots (U. lomvia) can be distinguished from slender-billed guillemots (U. aalge) by their relatively robust features, which include a heavier head and neck and a short, robust beak. They also have more black plumage and are missing most of the brown stripes on their sides.
Interesting fact: Species sometimes hybridize with each other, perhaps more often than previously thought.
Guillemots — they are diving birds with webbed feet, short legs and wings. Because their legs are set far back, they have a distinct upright posture, much like that of a penguin. Male and female guillemots look the same. Fledglings are similar to adults in terms of plumage, but have a smaller, thinner beak. They have a small rounded black tail. The lower part of the face becomes white in winter. The flight is strong and direct. Because of their short wings, their strikes are very fast. The birds make a lot of harsh giggling noises in nesting colonies, but are silent at sea.
Where does the murre live?
Guillemot completely populates the arctic and subarctic waters of the Northern Hemisphere. This migratory water bird has a wide geographic distribution. In summer, it settles on the rocky coasts of Alaska, Newfoundland, Labrador, Sakhalin, Greenland, Scandinavia, the Kuril Islands in Russia, Kodiak Island off the southern coast of Alaska. In winter, guillemots are found near open water, usually staying along the edge of the ice zone.
Guillemots live in the coastal waters of the following countries:
- Eastern Russia;
- Northern Ireland;
- Southern Norway.
Winter habitats range from the edge of the open ice south to Nova Scotia and northern British Columbia, and are also found off the coast of Greenland, Northern Europe, the Mid-Atlantic, the Pacific Northwest of the United States, and south in the Pacific Ocean to central Japan. After severe storms, some individuals may fly further south. This species is found in winter in large flocks in the open ocean, but some wandering individuals may appear in bays, estuaries or other bodies of water.
As a rule, they hunt far from the coast and are excellent divers, reaching depths of more than 100 meters in pursuit of prey. The bird can also fly at 75 miles per hour, although it swims much better than it flies. Guillemots also form large aggregations on rocky shores, where females usually lay their eggs on a narrow ledge along a steep sea cliff. Less commonly, it occurs in caves and crevices. The species prefers to settle on islands rather than on mainland coasts.
Now you know where the murre bird lives. Let's see what she eats.
What does the murre eat?
The predatory behavior of the murre varies depending 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, the murre's prey capture strategies are based on the potential energy gain from the prey item as well as the energy expenditure required to capture the prey.
The murre is a carnivorous bird and consumes a variety of marine life, including:
- large zooplankton.
Guillemot feeds underwater at depths of more than 100 meters, in waters with t less than 8 °C. Species slender-billed murres are skilled killers, they capture prey in active pursuit. On the other hand, thick-billed members of the genus spend more time hunting, but less energy searching for bottom prey, slowly sliding along the bottom in search of sediments or stones.
In addition, based on their location, U. lomvia may also have location-related dietary differences. At the sea ice edge, they feed in the water column and in the lower part of fast ice. In contrast, at the edges of the ice sheet, U. lomvia feed under the ice surface, on the seafloor, and in the water column.
Personalities and Lifestyles
Murmurs form large, dense aggregations in colonies on rock ledges where breeding occurs. Due to their clumsy takeoff, birds are considered to be more skilled swimmers than fliers. Adults and fledglings move long distances in migratory journeys from nesting colonies to the place of maturation and wintering. The chicks swim almost 1,000 kilometers, accompanied by male parents, on the first stage of their journey to the wintering grounds. During this time, the adults molt in their winter plumage and temporarily lose their ability to fly until new feathers emerge.
Interesting fact: Guillemots are usually active during the day. Using bird data loggers, scientists have determined that they travel between 10 and 168 km one way to their feeding grounds.
These seabirds also play a significant role in marine ecosystems based on their pelagic diet. It is believed that guillemots communicate using sounds. In chicks, these are mostly staccato sounds, characterized by a high-speed frequency-modulated outgoing call. Such a call is given when they leave the colony, and also as a way of communication between chicks and parents.
Adults, on the other hand, produce lower notes and sound rougher. These sounds are heavy, reminiscent of laughter «ha-ha-ha» or a longer, growling sound. When aggressive, guillemots emit a weak, rhythmic vocalization. Despite the fact that species can live together, in general, guillemots are quite scandalous and quarrelsome birds. They get along only with larger Arctic inhabitants, for example, with large cormorants. This helps murres when attacked by predators.
Social structure and reproduction
Guillemots begin breeding at five to six years of age and nest in large, dense, noisy colonies on narrow rock ledges. Within their colony, the birds stand side by side, forming a dense nesting habitat to protect themselves and their chicks from aerial predators. They typically arrive at nesting sites in the spring, from April to May, but as the ledges are often still covered in snow, oviposition begins in late May or early June, depending on sea temperature.
The females lay their eggs at about the same time to synchronize the time of hatching and the moment when the juveniles jump off the nesting ledges into the sea to make their long wintering migration. Female guillemots lay a single egg with a thick and heavy shell, greenish to pinkish in color, with patterned mottling.
Fun fact: Guillemot eggs are pear-shaped, so they don't roll when pushed on in a straight line, so you don't accidentally push him off a high ledge.
Females do not build a nest, but lay pebbles around it along with other debris, holding the egg in place with feces. Both male and female take turns incubating the egg over a 33 day period. The chick hatches in 30-35 days and both parents take care of the chick until it jumps off the rocks at 21 days old.
Both parents incubate the egg constantly, taking shifts of 12 to 24 hours. The chicks feed mainly on fish brought by both parents to the breeding site for 15-30 days. Usually chicks fledge at the age of about 21 days. After this point, the female goes to sea. The male parent stays to care for the chick for a longer period of time, after which he goes to sea with the chick at night in calm weather. Males spend 4 to 8 weeks with their offspring before they reach full independence.
Natural enemies of the murre
Guillemots are mostly vulnerable to aerial predators. Gray gulls have been known to prey on eggs and chicks left unattended. However, a dense nesting colony of guillemots, in which birds huddle side by side, helps protect adults and their young from air raids by eagles, gulls, and other birds of prey, as well as ground attack from arctic foxes. In addition, people, including groups in Canada and Alaska, hunt and consume muti eggs for food.
The most famous predators of saury include:
- burgomasters ( L. hyperboreus);
- hawks (Accipitridae);
- common crows (Corvus corax);
- Arctic fox (Vulpes lagopus);
- humans (Homo sapiens).
In the Arctic, people often hunt guillemots as a food source. Natives of Canada and Alaska annually shoot the birds near their breeding colonies or during their migration from the coast of Greenland as part of traditional hunting for food. In addition, some groups, such as the Alaskans, collect eggs for food. In the 1990s, the average household on St. Lawrence Island (located west of mainland Alaska in the Bering Sea) consumed between 60 and 104 eggs per year.
The average life expectancy of guillemots in the wild can be up to 25 years. In northeastern Canada, the annual adult survival rate was estimated at 91%, and by 3 years of age — 52%. Guillemots are vulnerable to man-made threats such as oil spills and nets.
Population and species status
As one of the most numerous seabirds in the northern hemisphere, the global population of murres is estimated by experts , has more than 22,000,000 individuals in a wide range. Therefore, this species does not approach the thresholds for a vulnerable species. However, threats remain, especially from oil spills and gillnets, as well as an increase in natural predators such as gulls.
The European population is estimated at 2,350,000–3,060,000 mature individuals. In North America, the number of individuals is increasing. Although the number of individuals in Europe has been increasing since 2000, a recent sharp decline has been seen in Iceland (home to almost a quarter of Europe's population). As a result of the reported decline in Iceland, the estimated and projected rate of European population decline over the period 2005-2050 (three generations) ranges from 25% to more than 50%.
This species is in direct competition with the fishery for food, and overfishing of certain stocks has a direct impact on guillemots. The collapse of the capelin stock in the Barents Sea resulted in an 85% reduction in the breeding population on Bear Island with no signs of recovery. Mortality from unregulated gillnet fishing can also be significant.
Fun Fact: Oil pollution from ships sunk during World War II is believed to have caused a dramatic decline in Irish Sea colonies in the mid-20th century, from which the affected colonies have yet to fully recover.
Hunting in the Faroe Islands, Greenland and Newfoundland is unregulated and can occur at unsustainable levels. No official assessment has been made of sustainable catch levels for this species. Guillemot is also sensitive to fluctuations in sea surface temperature, with a 1˚C temperature change associated with a 10% annual population decline.