Second North American Sea Duck Conference - Patuxent Wildlife ...

SECOND NORTH AMERICAN SEA DUCK CONFERENCE
PRELIMINARY CHARACTERIZATION OF MIGRATION AND BREEDING
GROUNDS ASSOCIATED WITH SURF SCOTERS WINTERING
IN WASHINGTON STATE FROM ONGOING TRACKING OF
SATELLITE AND VHF TRANSMITTERS
David Nysewander, Joseph Evenson, Bryan Murphie, Thomas Cyra, Briggs Hall, Dyanna
Lambourn, Don Kraege, Daniel Esler, Sean Boyd, John Takekawa, Susan Wainwright-De La Cruz,
and David Ward
Washington Department of Fish and Wildlife, Olympia, WA; nysewdrn@dfw.wa.gov
Scoters have experienced significant declines in numbers over the last 25 years in the marine
waters of Washington State; however little was known until recently of movements and population
demography of either the wintering surf scoter (Melanitta perspicillata) or the white-winged scoter
(Melanitta fusca) populations on the west coast and how they might relate to each other. The surf
scoter makes up, on average, 65% of the scoters found in Washington during the winter and may be
the largest contributor to the sea duck declines that have occurred here during this period. Large
concentrations of surf scoters were historically associated with some of the large herring spawning
events that occurred in Washington State in the winter and spring, even as late as early May. A
number of these herring spawning events have declined drastically over the last 25 years and we
wished to examine the relationship between surf scoters and these events in more detail as well as see
what part of the continental population of surf scoters contributed to those that winter in Washington.
Focus studies started in 2003 and are scheduled to continue until 2006 in Washington using satellite
and VHF transmitters for the purpose of documenting the patterns of distribution and fidelity to
winter and spring foraging areas, night concentrations, migration routes, breeding ranges, and
molting areas of those surf scoters associated with wintering in Washington. Fidelity to wintering
sites between years is examined to determine what proportion of surf scoters return to the marine
waters of Washington. We examine what evidence for immigration or emigration of scoters might
occur between the Pacific wintering areas between years. We also compare scoter population trends
from the USFWS & CWS Waterfowl Breeding Population and Habitat Survey, from the strata in the
Canadian interior where Washington scoters breed, with wintering trends from Washington State.
Three years of a four-year project have now been completed, suggesting the following: 1) Distinct
differences in distribution and movement exist between the two main scoter species, between male
and female scoters within each species, and between different flyway subpopulations of surf scoters,
such as those from San Francisco Bay and Puget Sound. 2) The time spent by adult (ATY) scoters
in marine areas is considerable, 9-10 months for males and 8-9 for females, and often includes the
molting flightless period. 3) Western Washington contains important wintering and spring staging
areas used by scoters as well as summer molting areas. 4) These spring staging areas also attract a
certain proportion of scoters wintering in San Francisco and Baja, Mexico. 5) Scoters return daily and
yearly often to the same locations, expressing considerable site fidelity. 6) Several different patterns
of scoter association with herring spawning and certain marine habitats were observed.
12 ANNAPOLIS, MARYLAND, USA NOV. 7-11, 2005