Densities of marbled murrelet, a state endangered and federally threatened species, have declined by nearly 5% per year between 2000 and 2024.  

Densities of the pigeon guillemot and rhinoceros auklet (both locally breeding species) are relatively stable, although the rhinoceros auklet shows evidence of a slight decline. 

Densities of scoters (surf, black, and white-winged scoter species combined) showed a period of consistent decline between 2000 and 2010 and then fluctuated between 2010 and 2022. Density estimates from 2023 and 2024 were relatively high, especially for white-winged scoters, moderating the evidence for a decline across the entire time series.  

Many factors influence the health of marine bird populations, both here and elsewhere in their range (including northern subarctic regions where scoters nest). Threats potentially limiting marine bird populations in Puget Sound include disturbance and loss of nesting, marine, and nearshore habitat as well as a decline in prey abundance and quality. Marine heat waves, or warm water events, also reduce prey availability and can result in starvation and increased prevalence of some marine bird diseases. 

Management actions to improve forage fish abundance, particularly Pacific herring, Pacific sand lance, and smelts would benefit marine bird populations, salmon, and orcas. 

Protection and restoration of critical habitats, such as estuarine and nearshore habitats, kelp, and sea grass, will benefit prey species for marine birds and many other species. It is a conservation priority to protect intact nesting habitats like mature forest and coastal bluffs and headlands that have nesting colonies of locally breeding seabirds. Additionally, land-use planning that accounts for sea-level rise and coastal squeeze is important for maintaining coastal wetlands and the food and habitat they provide for marine birds.