Razorbill

Name and taxonomy

Carl Linnaeus set up the genus Alca in 1758, in the tenth edition of Systema Naturae. The name Alca comes from the Norwegian word alke, and torda from a Swedish dialect word of Gotland. Both words already meant this bird before Linnaeus used them. The type locality is Stora Karlsö, an islet off the west coast of Gotland.

Older English writing calls the species the auk, the razor-billed auk or the lesser auk. French speakers call it petit pingouin, Spanish speakers alca común and German speakers Tordalk. The IOC accepts two subspecies, and the one in warmer water is slightly smaller. A third form was dropped once its extra bill furrow turned out to come with age.

Evolution and relatives

The razorbill belongs to the tribe Alcini with the two murres and the little auk. The great auk sat in the same group and went extinct in the middle of the nineteenth century. Some ornithologists would put the great auk back into Alca rather than keep it in Pinguinus. The razorbill is probably the nearest thing alive to a bird that people hunted out.

The genus was much richer in the Pliocene, and several fossil species are known. They have been found at Lee Creek Mine in the United States, in Belgium, in Italy and in Spain. Alca appears to have arisen in the western North Atlantic or the waters that are now the Caribbean. Its ancestors probably reached those seas through the open Isthmus of Panama during the Miocene.

Appearance

A breeding adult is black on the head, neck, back and feet, and white underneath. A thin white line runs from the eye to the tip of the bill. The bill is black, deep and flattened, with a blunt end and several vertical grooves. One groove carries a broken white mark that stands out at close range. The gape is bright yellow inside and the iris is dark brown.

The bird measures 37 to 39 cm and weighs 0.505 to 0.89 kg, which makes it heavy-set for an auk. The tail is long for the family, with the central feathers a little longer than the rest. In flight the feet do not stick out past the tail. Winter birds turn white on the throat and behind the eye, and the bill line fades. The bill also grows thinner out of the breeding season, and the grooves show less.

Habitat and range

The razorbill lives across the boreal and subarctic North Atlantic, with no counterpart in the Pacific. In North America it breeds from Hudson Strait and western Greenland down to the Gulf of Maine. In Europe it breeds from northwest Russia and Iceland south to Brittany and into the Baltic. Colonies sit on sea cliffs, boulder screes and offshore islands, always with a clear drop to the water. The species does well where the sea surface stays below 15 degrees Celsius.

North American birds winter offshore, from the Labrador Sea to New England. European birds gather in the North Sea, and some go as far as the western Mediterranean. Unlike other auks, razorbills will move into large estuaries with low salinity to feed. GBIF holds records from 48 countries, most of them from Britain, Sweden and the United States. Látrabjarg in Iceland held about 230,000 pairs in the mid-1990s, roughly 40 percent of the world total.

Diet and feeding

The razorbill eats mid-water schooling fish. Sandeels, capelin, sprats, herring and young cod make up most of the catch. Crustaceans and marine worms fill the gaps, and birds wintering off Newfoundland live mainly on crustaceans. In Labrador the diet shifts from capelin to small sculpins and krill once the chicks hatch.

The bird dives with its wings half folded and its feet spread, and it swims after fish underwater. Most feeding happens around 25 metres down, though a razorbill can reach 120 m. One study off the Isle of May measured an average dive of 35 seconds. Divers spread out rather than work in a group. A single dive can bring up several small fish at once.

Adults spend about 44 percent of their time at sea foraging. During incubation a bird may fly more than 100 kilometres out to feed. Once there is a chick to feed, the parents work closer in, around 12 km from the colony. A parent carries the fish crosswise in the bill, usually one to six at a time. Deliveries peak at dawn and fall away in the four hours before dark.

Behaviour and social life

Razorbills are colonial, but the nests sit metres apart rather than shoulder to shoulder. That spacing means less fighting than in a guillemot colony. On land the bird squats on its ankles and shuffles about, holding the body fairly level. It is more agile in the air and on the water than the other large auks. North American birds leave land for the whole winter, while many European birds stay near the cliffs.

Before laying, large groups gather on the water and behave in two set ways. In one, the birds dive and circle together and then come up head first with open bills. In the other, a long line of birds swims one way, weaving across each other. Pairs preen each other about the head and neck, sometimes for six or seven minutes. Both members of a pair defend the nest site through the season.

Communication and senses

Much of the signalling is done with the bill rather than the voice. In bill clicking a bird knocks its mandibles together while shaking its head slowly from side to side. In bill vibrating it throws the head back and shivers the lower mandible. Mutual preening settles tension between partners and is a ritual of its own.

Courting pairs touch bills and follow one another through long looping flights. The white line on the bill and face is brightest in the breeding season, which suggests it is a signal. Underwater the bird hunts by sight, so clear shelf water probably matters to it. A chick probably calls to its parent from the sea after it leaves the cliff.

Reproduction and life cycle

The female chooses her mate, often after letting several males compete for her. The pair then stays together for life, and their system is described as female-enforced monogamy. A pair may mate up to 80 times in the 30 days before the egg is laid. At least half of females also copulate with neighbouring males on another ledge. Birds first breed at three to five years old, and old pairs sometimes skip a season.

The nest is a crevice on a cliff or a gap under boulders, at least 10 centimetres back from the open ledge. Crevice sites lose fewer eggs to predators than open ledges. Some pairs drag a little stone, lichen or dried droppings to the spot, but most lay on bare rock. The same site is often used year after year. A pair may also take over an old puffin or rabbit burrow.

The female lays one egg a year, from late April into early June. It is pointed at one end, creamy white to pale brown, and blotched dark brown. Both parents incubate in turn for about 35 days. The chick hatches at about 60 grams and shelters under a parent's wing for its first days. After 17 to 23 days it jumps from the cliff, still flightless, and the father follows it to sea. Average life expectancy is about 13 years, and one ringed British bird lived at least 41 years.

Predators and threats

Adult razorbills are taken by great black-backed gulls, by peregrine falcons and by ravens, crows and jackdaws. Gulls and ravens take the eggs, which are large and rich in fat. Arctic foxes and polar bears kill adults, eggs and chicks in the north of the range. A chick that leaves the cliff alone, rather than with the others, is easier for a gull to catch. An adult in danger escapes by diving.

Oil spills are the threat that does the most harm at sea. Birds also drown after they become tangled in fishing nets. Overfishing thins the shoals of small fish the species depends on. Hungry birds have turned up well outside the usual range while searching for food. Damage to a cliff colony removes nest sites that pairs would otherwise reuse for years.

Population and conservation

The IUCN Red List rates the razorbill as Least Concern. The world total is put at 838,000 to 1,600,000 mature birds. Numbers fell between 2015 and 2021 and now appear stable or rising. Annual survival of an adult runs between 89 and 95 percent.

National lists are harsher than the global one in several countries. France lists the species as Critically Endangered, and Norway and Estonia as Vulnerable. The Norwegian list puts it at Endangered on Svalbard and Jan Mayen. The French colony on Île Rouzic fell from 600 pairs in 1960 to 30 pairs by 2006. Bempton Cliffs in Yorkshire held 30,673 pairs in 2022, so the picture varies with the coast.

Relationship with humans

People took razorbills for eggs, meat and feathers into the early twentieth century. That harvest cut the world population hard. The Migratory Bird Treaty Act protected the species in the United States in 1918. Cliff colonies probably draw more birdwatchers than any other use of the bird now.

Researchers use the razorbill as a model for the study of bird mating behaviour. Its habits at sea may make it a useful marker of the state of shelf fish stocks. No one keeps the bird, and it appears never to have been kept in any numbers. The threats that remain probably come from shipping, fishing and building on the coast.

In culture and myth

On St Kilda in Scotland, men climbed the sea stacks with ropes to gather eggs and birds. Razorbill and guillemot eggs were taken there until the late 1920s. The islanders buried the eggs in peat ash so that they would keep through the winter. People said the eggs tasted like duck eggs and fed a household as well. The last 36 islanders left St Kilda in 1930, and the fowling ended with them.

In Nordic naming the bird gave its own words to science, through Norwegian alke and Gotland torda. In British birdwatching the razorbill appears as a living echo of the great auk. In French the name petit pingouin probably keeps an old confusion between auks and penguins alive. In Icelandic seabird tradition the cliffs that hold the species appear to have been harvested for centuries.