The Birds Vital Sign tells us about the health of populations of native resident and migratory bird species associated with Puget Sound. Each winter, thousands of seabirds, sea ducks, and waterfowl converge in the relatively calm and food-rich waters of Puget Sound. In summer, seabirds and landbirds are busily raising and attending their young in the Sound’s forests and coastal environments. In spring and fall, the mudflats bustle with shorebirds that stop to feed and rest during migration. During the non-breeding season, large flocks of marine waterfowl and seabirds aggregate to rest and feed in nearshore waters. Because it draws such a variety and abundance of bird life, Puget Sound supports over a dozen Important Bird Areas and offers ample birdwatching opportunities.

The Birds Vital Sign measures trends in the abundance of both the marine and terrestrial birds. Each of these indicators integrates population information from multiple species that represent different diets and habitats. The marine bird indicator tracks the abundance of breeding season at-sea densities of marbled murrelet, rhinoceros auklet, and pigeon guillemot, and non-breeding season at-sea abundance trends for surf, white-winged and black scoters. Each of these species are considered highly dependent on the marine environment of Puget Sound and the greater Salish Sea.  The terrestrial bird indicator measures the change in forest interior and human-associated terrestrial bird populations that reside most, if not all, of the year in the Puget Sound basin.


Key Vital Sign Messages

 Rhinoceros auklet with herring. Photo P. Hodum

Indicator Species

  • Marine bird indicator - Marbled murrelet, rhinoceros auklet, and pigeon guillemot breed locally in Puget Sound and the Strait of Juan de Fuca, whereas the three scoter species (surf, black, and white-winged) overwinter here and breed elsewhere.
  • Terrestrial bird indicator - Forest interior indicator species include golden-crowned kinglet, varied thrush and brown creeper. Human-associated indicator species include American crow, rock pigeon, house sparrow, house finch, and European starling.

Population Trends

  • Marine bird indicator – Species in the marine bird indicator show different abundance patterns over time. Marbled murrelets, a federally threatened species, have declined by nearly 5% per year since surveys began in 2000. Scoter density has also declined by 2% per year. In contrast, Sound-wide trends for pigeon guillemots and rhinoceros auklets suggest stable populations.
  • Terrestrial bird indicator –The breeding population abundance of forest interior species has steadily declined since 1968 while human-associated species have remained relatively stable. The declining trend in forest interior species is driven by declines in the golden-crowned kinglet, the most abundant of the three indicator species. Declines in Puget Sound forest species parallel patterns of loss in bird abundance across all western forests.

Factors Influencing Populations

  • Habitat alteration and degradation, changes in prey populations, disease, and contamination from toxic chemicals may all affect bird abundance and distribution. Human and environmental pressures in parts of species’ ranges outside of Puget Sound can also lead to changes in the number of birds we see locally in Puget Sound.
  • Changing ocean and climate conditions associated with climate change can:
    • disrupt historical patterns of prey abundance and diversity, resulting in inadequate food or changes to the food quality having impacts of unknown severity if sustained for multiple years; and
    • increase the prevalence of disease in seabird breeding colonies in Puget Sound through increases in sea surface temperatures.

How You Can Participate

Other Resources

Contributing Partners

The following organizations contribute marine bird monitoring data to the Birds Vital Sign for Puget Sound: