Marbled Murrelet

The Marbled Murrelet is a small, endangered seabird of the Salish Sea with a remarkable life cycle. Unlike most seabirds, it nests high in old-growth forests miles inland, relying on both ancient forests and healthy coastal waters to survive. Unfortunately, the marbled murrelet population in Washington is low and declining. Because of its breeding association with old forests, their populations have been severely affected by loss of mature and old forest habitat. Food resources in the marine environment may also influence population status. Even where numerous, it is usually seen on the water in pairs or aggregations of pairs, not in large flocks; pairs flush from the water in front of approaching boats, fly away low with very rapid wingbeats.

Physical description

The marbled murrelet is a small (10 inches in length), chunky seabird. Its beak is black and slender. Breeding plumage has an overall brownish ‘marbled’ look. Adult non-breeding plumage is a black crown with a white ear patch, throat and underside, black nape and back, and black wings with white scapulars (top of wing). Juvenile plumage is similar to adult non-breeding but duskier overall. 

Ecology and life history

Marbled murrelets are seabirds that forage in marine waters but nest in forests. In Washington, marbled murrelets nest in mature and old-growth conifer forests, and sometimes in comparatively younger forests with residual old-growth trees. They locate their nest in a depression on a mat of moss, lichen or debris accumulations on large branches. Marbled murrelets appear to establish long-term pair bonds and fidelity to nesting areas and nest trees.

Small schooling fish (such as Pacific anchovy, Pacific herring, candlefish, and Pacific sand lance) make up most of the diet, which may include small crustaceans when fish are not abundant. Marine foraging areas are usually within 1.2 to 3 miles of shore, typically in waters less than 100 feet deep.

Geographic range

The marbled murrelet inhabits the nearshore marine environment in western North America. In Washington, this species is an uncommon resident. It is found in marine waters in general proximity to nesting habitat. It is most abundant in northern Puget Sound and the Strait of Juan de Fuca, and least abundant along the coast of southwestern Washington. The primary factor influencing breeding distribution is likely the availability of suitable nesting "platforms" (such as large branches) within close proximity to marine water foraging areas.

Population Status

Surveys indicate highest nesting presence is on the Olympic Peninsula, the northern Cascades and in limited remaining habitat in southwest Washington. At-sea population monitoring from 2001 to 2015 indicated a 4.4% decline in the murrelet population annually, which represents a 44% reduction since 2001. The 2015 population estimate for Washington is about 7,500 birds. Since 1993 nesting habitat losses due to timber harvest in Washington have been substantial and at-sea population monitoring from 2001 to 2024 indicated nearly a nearly 5.0% decline in the murrelet population annually. The 2023 population estimate for Washington was 4,400 birds (McIver et al. 2025), down from the estimated 7,500 in 2015.

Sustained low juvenile recruitment has been identified as a main cause of their decline, but research investigating the cumulative effects from threats on individuals and populations is ongoing. Vital demographic data are lacking, and nest success is influenced by both terrestrial and marine factors, such as the availability of nesting sites, amount of nesting habitat, nest predation, and prey availability and quality. Human marine activities appear to influence murrelet abundance and distribution in the Salish Sea. Declines in populations of forage fish species resulted in an increased consumption of lower trophic level food sources (invertebrates). Ultimately, changes to the marine food web may have influenced reproductive output. Federal and state landscape plans and Forest Practices Rules, implemented to help stem the loss of higher quality nesting habitat, have been beneficial but have not led to recovery goals being met.

Marbled murrelets continue to experience significant population declines across much of their range, with the steepest long-term declines in Washington (USFWS 2024). Their low reproductive rate means that high survival rates for young are essential for population growth. Despite initiatives such as federal forest management plans, habitat conservation strategies, and state Forest Practices Rules, habitat loss continues. Coupled with the reduction in prey availability and quality, these factors have likely adversely impacted nest success and the survival of juveniles. With projections of accelerated ocean warming and increased global timber demand, the threats to murrelets are expected to intensify, further jeopardizing the two key habitats on which they depend (Betts et al. 2020). Without effective, immediate solutions to address these pressing threats, the situation for marbled murrelets is likely to deteriorate, and the species could be lost from some regions in the coming decades.

Sources:

WDFW https://wdfw.wa.gov/sites/default/files/publications/02627/draft_wdfw02627.pdf

Audobon Society https://www.audubon.org/field-guide/bird/marbled-murrelet

The Salish Sea School https://www.thesalishseaschool.org/copy-of-research