Testing the feasibility and effectiveness of a fall Steller’s eider molt survey in southwest Alaska

Wilson, Heather M.
Larned, William W.
Bowman, Timothy
Fischer, Julian B.
USFWS -Migratory Bird Management - Alaska
Publication Date: 

Since 1992, U.S. Fish and Wildlife Service, Migratory Bird Management has flown a spring
aerial survey in southwest Alaska to monitor trends in the Pacific population of Steller’s eiders
and improve understanding of habitat use and timing of spring migration. Due to constraints with
the traditional spring survey, we sought to test
the feasibility of an alternative monitoring approach using photography of fall molting flocks
along the Alaska Peninsula. Our goal was to determine whether different survey timing and methods
could provide a more precise and cost effective annual index to track the Pacific Steller’s eider
population. We reasoned that a fall photographic survey could be more effective based on: 1) better
timing (molt being easier to target than spring staging, as flocks are sedentary), improved flock
estimation (better precision using photographs than ocular estimates alone), and weather (early
fall typically has longer periods of favorable weather). From 27‐30 August 2012, we conducted
photographic surveys of molting Steller’s eiders at major lagoons along the Alaska Peninsula (King
Salmon to Izembek NWR), with replicate surveys at the Seal Islands and at Izembek and Nelson
lagoons. Combined counts for the Alaska Peninsula totaled 50,404 birds, with an average of 9,764
birds at Seal Islands, 35,549 birds at Nelson lagoon, 4,418 birds at Izembek lagoon, and 943 birds
scattered between Port Moller (602) and Port Heiden (341). Results from 2012 provided defensible
population estimates and repeatable methodology. We discuss the feasibility of photographic
methods, compare current and historic Steller’s eider population surveys, and outline benefits and
constraints of a fall survey as an index to the Pacific population.

KEY WORDS Alaska, Steller’s eider, population index, photographic survey, molt, Polysticta

Citation Information: 
Wilson, H. M., T. D. Bowman, W.W. Larned, and J. B. Fischer. 2012. Testing the feasibility and effectiveness of a fall Steller’s eider molting survey in southwest Alaska. Unpublished Report. USFWS, Migratory Bird Management, Anchorage Alaska. http://alaska.fws.gov/mbsp/mbm/waterfowl/surveys/pdf/swsteimolt.pdf