Shorebird surveys in western Alaska

Abstract

Surveys for breeding shorebirds were conducted during 2001-2002 in four National Wildlife Refuges (NWRs) in western Alaska - Alaska Maritime, Alaska Peninsula, Yukon Delta and Selawik. The sizes of our study areas on and adjacent to these four refuges were 9,243 km 2 , 24,493 km 2 , 853 km 2 , and 15,170 km 2 , respectively. Eleven sites were selected non-randomly, 3 in the Alaska Maritime NWR, 6 in the Alaska Peninsula, and one each in the other two NWRs. Survey and analytic methods are described in Chapter 2. Rapid surveys were conducted on 224 plots; 2,163 indicated pairs of shorebirds were recorded of which 1,485 were judged to be nesting in the surveyed plots. Detection ratios were estimated using intensive plot data from northern Alaska as well as from two plots on the Yukon Delta NWR. The highest estimated densities (shorebirds/km 2 ) were on the Yukon Delta Study Area: 416 in wetlands and 300 in moist areas. The estimated densities on the Alaska Peninsula Study Area were 118 in wetlands and 62 in uplands. Other densities were markedly lower. Estimated numbers of shorebirds were 62,000 (CV = 0.58), 1,804,000 (CV = 0.32), 310,000 (CV = 0.11), and 390,000 (CV = 0.35), in the Alaska Maritime, Alaska Peninsula, Yukon Delta, and Selawik study areas, respectively. The former two estimates were affected by selection bias of unknown magnitude and so should be regarded with caution. A small estimate was generated for the Yukon Delta Study Area because it covered only about 1% of the Yukon Delta NWR. We identify several species-specific estimates from our study which appear inconsistent with previous continental estimates. This pilot study provides preliminary estimates of species composition and density in the surveyed areas. By incorporating several region-specific modifications to the sampling protocols for future surveys, we believe that the Arctic PRISM method is suitable for covering large areas in western Alaska.