NATURAL HISTORY

MARBLED MURRELET } Brachyramphus marmoratus
FAMILY: Alcidae

DESCRIPTION: Marbled murrelets are small, plump, puffin-like seabirds with short necks and tails; slender, pointed bills; and long, narrow wings. Adults have a sooty-brown body marbled with a light brown and gray underside. Nonbreeding plumage reveals a black head and body with a white neck collar, black wings with a white wing patch, and white underparts. Males and females have similar plumage in all seasons.

HABITAT: Marbled murrelets are seabirds, feeding near shore within three miles of the coastline. They are commonly found inland during the summer breeding season, up to 50 miles from the ocean, where they nest in old-growth coniferous forests. For nesting, the birds require forests with high canopy closure and large trees with deformities for nest platforms — characteristics that are common to old-growth and mature forests. The exception is in Alaska, where small numbers of marbled murrelets nest on the ground on rocky slopes near the ocean.

RANGE: Marbled murrelets are found along the Pacific Coast of North America from the Aleutian Archipelago and southern Alaska to central California just south of the San Francisco Bay.

MIGRATION: Marbled murrelets are present near their breeding range year-round. They can also be found wintering a little further south, along the coast of Southern California. Murrelet pairs return to the same forest grove each year.

BREEDING: Unlike many seabirds, marbled murrelets do not form large colonies when breeding. Instead, they fly inland where they nest in old-growth forests. Between April and July, female murrelets will lay one egg on the limb of a large conifer. Both sexes incubate the egg in alternating 24-hour shifts for about a month until it hatches. Fledging takes another month, during which the chick’s parents fly frequently between the nest and the ocean, returning from each flight with food. Marbled murrelets are relatively monogamous and establish long-term pair bonds.

LIFE CYCLE: Marbled murrelets live an average of 10 years and reach sexual maturity at two to three years of age.

FEEDING: Marbled murrelets feed on a wide variety of small fish and invertebrates, including sand eels, herring, anchovy, capelin, and sardines. They are proficient divers, using their wings to swim in pursuit of underwater prey.

THREATS: Habitat loss due to commercial logging of old-growth forests has been and continues to be the greatest threat to the marbled murrelet. Other threats include climate change affecting ocean conditions, incidental bycatch in commercial fishing nets, increases in predator populations, oil spills, and chemical dumping and other marine pollution.

POPULATION TREND: Historical estimates indicate that at least 60,000 marbled murrelets were once found along the coast of California. With the decimation and fragmentation of coastal old-growth forests, these birds have likely suffered a 90-percent reduction in numbers. In 1997, the U.S. Fish and Wildlife Service estimated that the marbled murrelet population in the Pacific Northwest was declining by 4 to 7 percent each year. More recent demographic models indicate that populations in Washington, Oregon, and California could be extinct within the next 50 years. Populations in British Columbia and Alaska, while more numerous, have declined by at least 70 percent over the past 25 years.

Marbled murrelet photo by Gus Vliet Van, USFWS, FPWC