Steller's Eider spring migration surveys

Annual spring aerial surveys were conducted most years from 1992 to 2008, to monitor the population status and habitat use of Steller's eiders (Polysticta stelleri) staging for spring migration in southwestern Alaska. Since the timing of migration varies among years, we conducted two to three replicate shoreline surveys each survey year through 1997, to target peak presence of eiders within the survey area prior to their departure to arctic nesting grounds. Fiscal constraints in subsequent years limited us to one survey per year through 2007, the timing of which was carefully scheduled using available information on sea ice, weather and observations from local contacts. In 2008 we again completed two surveys because of low confidence in timing and results of the early survey. During each survey we recorded visual estimates of Steller's eiders and all other identifiable water birds and marine mammals along shorelines and within estuaries and shoals where Steller's eiders and other sea ducks were known to congregate during migration. In each year where multiple surveys were completed, the highest Steller's eider count was used as that year's population estimate for trend analysis. Annual estimates are 72,953 (2000), 60,656 (2001), 56,704 (2002), 77,369 (2003), 82,772 (2004), 79,022 (2005), 87,400 (2007) and 70,480 (2008) . We suspect that the low population estimates obtained from 2000 through 2002 were due in part to poor survey timing (a portion of the eiders moved northward during the survey, thus escaping detection by the survey crew). This hypothesis was supported by satellite telemetry data which indicated migration within the study area during the survey of 2002. Long-term survey data indicate a 2.6 percent average annual decline in Steller’s eiders using this migration corridor (R2 = 0.32), but the trend since 2002 has been more level (-1 percent per year, R2 = 0.10). Maps illustrate the distribution of Steller’s eiders and other selected species within the survey area in 2008. A persistent pattern of habitat use by Steller's eiders and most other sea duck species among years is evidence of the importance of certain areas to staging and migrating waterfowl. Many of these areas receive consistent intensive use by waterfowl in other seasons as well.

Data and Resources

Additional Info

Field Value
Maintainer Brent Frakes
Last Updated July 29, 2019, 22:13 (CDT)
Created July 29, 2019, 22:13 (CDT)
Identifier FWS_ServCat_85065
Issued 2008-12-09
Modified 2008-12-09
Theme ["Unpublished Report"]
accessLevel public
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