Common murre

Murres eat fish.

A murre dives under the water and swims fast to catch little fish. Then it brings a fish back to its chick.

Common murres eat mostly fish such as herring, cod, capelin, sand lance and haddock. They also eat crustaceans, marine worms and squid.

To catch them, murres dive underwater and swim after the fish. Their deepest dives reach about 170 to 230 meters. They hunt mostly in daylight. In the nesting season, parents fly back and forth between the cliff and the sea, often feeding close to the colony but sometimes traveling tens of kilometers.

The common murre is a pursuit-diving seabird that forages mainly in daylight (IUCN). Schooling fish are the key prey in the breeding season, though bottom-living fish can matter too: in the UK sand eels and herring-family fish dominate, while in Labrador, Canada, shannies made up 84 percent of the diet in 1996 and capelin 44.7 percent in 1997.

Maximum dive depths are about 170 to 230 meters. Foraging distances vary by colony and year, often within tens of kilometers, and birds feed where fish concentrate, such as over ridges and at fronts between bodies of water of different temperature.

Murres nest together in huge, noisy crowds on cliffs.

Lots and lots of murres can share one cliff! They also swim together in big groups on the sea.

Murres are very social. They nest in colonies, crowded together on cliff ledges, and the RSPB calls these busy places seabird cities. Some cliffs are packed with murres.

When murres leave the cliff to go fishing, they often splash down on the water and gather in big floating groups, called rafts, near the colony before flying off to feed.

Breeding is highly colonial: incubating birds sit so close that neighbors can touch (Audubon), and the RSPB describes guillemots as among the most common birds of Britain's seabird cities. Departing birds usually splash down to form large rafts close to the colony before heading to foraging areas (IUCN).

One parent always remains with the chick while the other forages. Most foraging happens in daylight. Studies at colonies such as the Isle of May in Scotland and the Pribilof Islands in Alaska have tracked how far murres travel to feed.

There are millions of common murres.

But they need lots of fish and clean seas. People help murres by keeping the ocean clean and leaving enough fish for them.

Common murres are listed as Least Concern, and there are millions of them. But they face many problems. Oil spills are very dangerous because murres spend so much time on the water. Overfishing can leave them short of food, and some are caught in fishing nets.

Murres are also sensitive to warmer seas, which change the food they depend on. Scientists watch murre colonies closely to learn how the ocean is changing.

The IUCN's 2018 assessment lists the species as Least Concern, using an older (1996) estimate of about 18 million individuals, with North American numbers increasing but sharp declines in Iceland. Threats include competition with fisheries (the collapse of Barents Sea capelin cut Bear Island's breeding population by 85 percent), gillnet bycatch, oil pollution, unregulated hunting in parts of the North Atlantic, and sensitivity to sea temperature.

The most dramatic event came after the 2014-2016 northeast Pacific marine heat wave known as 'the blob'. A 2024 study led by the U.S. Fish and Wildlife Service estimated that about 4 million Alaska murres, about half the state's population, died, mainly because changes in the food web left them without enough food. Colonies had not recovered by 2022.