Wildlife Research and Management - Wildlife Research
Date Published: February 2013
Number of Pages: 23
Author(s): Monique M. Lance, Scott F. Pearson, Martin G. Raphael, and Thomas D. Bloxton, Jr.
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, US Fish and Wildlife Service, and other state, federal and private researchers have participated in a program to estimate marbled murrelet population size and trends 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 (Conservation Zones) throughout this range, two of which are located in Washington; Zone 1 includes the Strait of Juan de Fuca, Puget Sound, Hood Canal and the San Juan Islands and is monitored by the USDA Forest Service Pacific Northwest Research Station; Zone 2 includes the Washington outer coast and is monitored by Washington Department of Fish and Wildlife. This report focuses on monitoring results from Conservation Zones 1 and 2 during the 2012 monitoring season (15 May - 31 July).
The marbled murrelet population estimate for all zones in the Northwest Forest Plan area (San Francisco Bay to the Canadian border) in 2012 was 21,284 (95% confidence interval 16,700 - 25,867). The population estimate has ranged from 16,798 – 23,673 over the 12 years of monitoring. The population estimate for Puget Sound and the Strait of Juan de Fuca in 2012 (Zone 1) was 8,442 birds (95% confidence interval = 5,276 – 12,030 birds) with a 3.17% (standard error = 2.00%) average annual rate of decline for the 2001-2012 period. The population estimate for the Washington coast for 2012 (Zone 2) was 1,240 birds (95% confidence interval = 833 - 1,504 birds) with a 7.59% (standard error = 2.01%) average annual rate of decline for the 2001-2012 period. For Washington State (Zones 1 and 2 combined) the estimate of annual rate of change in murrelet density was -4.07% (95% confidence interval -7.47%, -6.02%) for the 2001-2012 period.
Lance, M.M., S.F. Pearson, M.G. Raphael, and T. D. Bloxton, Jr. 2013. Washington 2012 at-sea marbled murrelet population monitoring: Research Progress Report. Washington Department of Fish and Wildlife, Wildlife Science Division and USDA Forest Service Pacific Northwest Research Station, Olympia, WA.
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