2013 Washington At-Sea Marbled Murrelet Population Monitoring: Research Progress Report

In 1992, the marbled murrelet (Brachyramphus marmoratus) was listed as a Threatened species by U.S. Fish and Wildlife Service in California, Oregon and Washington under the Endangered Species Act and as Threatened by Washington State. A federal recovery plan was published in 1997 that outlined recovery strategies including developing and conducting standardized at-sea surveys. In addition to meeting the requirements of the Endangered Species Act, long-term marbled murrelet monitoring was designed to evaluate the effectiveness of the Northwest Forest Plan (Madsen et al. 1999), which is a large-scale ecosystem management plan for federal lands in the Pacific Northwest.

Washington Department of Fish and Wildlife, USDA Forest Service Pacific Northwest Research Station, U.S. Fish and Wildlife Service, and other state, federal and private researchers have participated in a program to estimate marbled murrelet population size and trends during the breeding season between San Francisco Bay and Washington state since 2000. The information derived from this effort is the only information available to assess population size and trends in this geographic area for this species. This monitoring program uses at-sea line transects within 8 km of the Washington, Oregon, and northern California coastline in the area covered by the Northwest Forest Plan. There are five monitoring zones or Conservation Zones throughout this range, two of which are located in Washington: (Zone 1) Strait of Juan de Fuca, Puget Sound, Hood Canal and the San Juan Islands; and (Zone 2) the outer coast of Washington. Both zones are now monitored by the Washington Department of Fish and Wildlife, but the U.S. Forest Service monitored Zone 1 from 2000-2012. This report focuses on monitoring results from Conservation Zones 1 and 2 during the 2013 monitoring season (15 May - 31 July).

The population estimate for Puget Sound and the Strait of Juan de Fuca in 2013 (Zone 1) was 4,395 birds (95% confidence interval = 2,275 â€" 6,740 birds) with a -3.88% (standard error = 1.73%) average annual rate of decline for the 2001-2013 period (p = 0.0499). The population estimate for the Washington coast for 2013 (Zone 2) was 1,257 birds (95% confidence interval = 920 â€" 1,846 birds) with a -7.37% (standard error = 1.70%) average annual rate of decline for the 2001-2013 period (p = 0.0016). For Washington State (Zones 1 and 2 combined) the estimate of annual rate of change in murrelet density was -4.65% (standard error = 1.33%) for the 2001-2013 period (p = 0.0059).