Overview
Common murres (Uria aalge) are sleek, powerful seabirds in the Alcidae family, which also includes puffins, guillemots, murrelets and auklets. They are found in colder circumpolar waters of the North Pacific and North Atlantic Oceans. In the United States, common murres are year-round residents along Alaska’s coastline, the Pacific Northwest, and California’s Channel Islands. In winter, their range extends along the U.S. and Canadian Atlantic coast, from Newfoundland to Cape Cod, Massachusetts, occasionally reaching Virginia. Their presence is rare from Cape Cod to Long Island, New York, and extremely uncommon from New Jersey to Maryland.
Adult common murres weigh between 800-1,125 grams (28.2-39.7 ounces) and measure 38-43 cm (14.9 to 16.9 inches) in length-- about the size of a bowling pin. These pursuit-diving piscivorous birds, catch fish by using their wings to propel them underwater, diving to depths most other seabirds cannot reach. They consume about 30% of their weight in food daily. Certain fish species , such as Capelin, are more nutritionally valuable to them than others (e.g. a young-of-year Alaska Pollock). They are also strong fliers, capable of traveling long distances between their breeding areas and feeding waters.
Common murres have a streamlined black-and-white body built for swimming, and during the breeding season, their heads are entirely black. Their long, thin bills are equipped with an interior roof lined with “denticles,” or sharp nubs that help them catch and carry fish. They eat mostly small schooling fish, including Capelin, Northern Anchovy, and Pacific Herring, in addition to invertebrates and crustaceans.
While common murres spend a majority of their time at sea, they come ashore to nest in large breeding colonies on rocky cliffs above the ocean. Nesting locations demonstrate a preference for bare rock, where they lay a pyriform (pear-shaped) egg with a pointed end. This shape helps prevent the egg from rolling off the edge of the cliff. Each egg has unique colors and patterns, helping parents locate their egg in dense colonies.
Threats to common murre populations include introduced predators (rats), oil spills, gill nets, pollution, changing marine conditions that affect food webs and availability of preferred food items.