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WDFW LogoConservation

For more information on species & ecosystem science:

Wildlife Science

Fish Science

Habitat Science

Lead Scientists: Scott Pearson
  Monique Lance

Ecoregions: Puget Trough, Northwest Coast

Ecological Systems: Not Available for Research Area


The six marbled murrelet conservation zones


WDFW field biologists Ian Snider and Andrew Spees surveying marbled murrelets.


The six marbled murrelet conservation zones


Seabird Ecology

Marbled Murrelet Population Trends

Project Description

The Marbled Murrelet was listed as a Threatened species in California, Oregon and Washington in 1992 by U.S. Fish and Wildlife Service under the Endangered Species Act. A recovery plan was published in 1997 that outlined recovery strategies including developing and conducting standardized at-sea surveys. Along with federal and state researchers, Washington Department of Fish and Wildlife has participated in a program to estimate marbled murrelet population size and trends since 2000 and WDFW also participated in the testing of various survey methods. This at-sea monitoring program uses line transects (DISTANCE sampling) within 8 km of the Washington, Oregon, and northern California coastline in the area covered by the Northwest Forest Plan (see map). There are six marbled murrelet conservation zones but only zones 1-5 are monitored as part of this monitoring program. Two of these zones are located in Washington; Zone 1 includes the Strait of Juan de Fuca, Hood Canal and the San Juan Islands and is monitored by the Pacific Northwest Research Station, U.S.D.A. Forest Service; Zone 2 includes the Washington outer cost and is monitored by Washington Department of Fish and Wildlife.

This project is currently funded by U.S. Fish and Wildlife Service but has received funding from Washington Department of Natural Resources and WDFW.

Key Findings

  • Range-wide results (California, Oregon and Washington
    • From 2000 to 2010, population estimates for the area ranged from 16,700 to 23,700 birds, with a 2010 estimate of 16,700(95% confidence interval: 13,075-20,307).

    • For the 2001-2010 time period, the coast U.S. population of the murrelet has been declining at an annual rate 3.7% (standard error: 0.40%). Population declines are greatest in Washington’s waters. 

  • Washington results
    • The population estimate for the area covered by Puget Sound and Strait of Juan de Fuca (Zone 1) in 2010, was 4,393 (95% confidence interval = 2,689-6,367 birds). The population estimate for the Washington coast for 2010 (Zone 2) was 1,286 birds (95% confidence interval = 650-1,946 birds).

    • From 2001-2010, the number of marbled murrelets in Puget Sound and the Strait of Juan de Fuca has declined by 7.4% per year (standard error: 1.6%) and there is a nearly significant decline of 6.5% per year (standard error: 2.91%; p = 0.0624) for the Washington coast. When combining results from all Washington marine waters, there is a 7.3% annual decline over the 10 year period (standard error: 0.76%: p = 0.0007).

What's New

  • The range-wide recovery team is summarizing the range-wide and conservation zone 10-year trends for an upcoming publication.
  • U.S. Forest Service researcher, Martin Raphael, is leading an effort to evaluate the relative effect of at-sea and nesting habitat factors on murrelet population trends.
  • Data gathered on other seabirds while conducting murrelet monitoring is being used to asses population trends.  For details see “Puget Sound and Washington Coast Seabird Population Trends.”