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

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SECOND NORTH AMERICAN SEA DUCK CONFERENCE PRELIMINARY CHARACTERIZATION OF MIGRATION AND BREEDING GROUNDS ASSOCIATED WITH WHITE-WINGED SCOTERS WINTERING IN WASHINGTON STATE FROM ONGOING TRACKING OF SATELLITE TRANSMITTERS Joseph R. Evenson, David R. Nysewander, Bryan L. Murphie, Thomas A. Cyra, Briggs Hall, Dyanna Lambourn, Don Kraege, Daniel Esler, and Sean Boyd. Washington Department of Fish & Wildlife; evensjre@dfw.wa.gov A number of marine birds and sea ducks have experienced significant declines in numbers over the last 25 years in the marine waters of Washington State, with scoters composing one of the larger avian biomasses associated with this decline. However, little was known until recently of movements and population demography of either of the two more numerous wintering scoter species populations, the surf scoter (Melanitta perspicillata) and the white-winged scoter (Melanitta fusca), on the west coast and how they might relate to each other. The white-winged scoter makes up roughly 35% of the scoters found in Washington during the winter on average. Focus studies started in 2003 on both species, but the effort devoted to white-winged scoters involved implanting them with only satellite transmitters. Our first source of outside funding directed us to look at this species, so as to complement an ongoing similar effort by scientists in the Strait of Georgia that was looking at white-winged scoters. These initial studies are scheduled to continue until 2006 in Washington using satellite transmitters primarily for the purpose of documenting the patterns of distribution and fidelity to winter and spring foraging areas, night concentrations, migration routes, range of breeding sites, and molting areas of those adult scoters wintering in Washington. Between years wintering site fidelity was examined to determine what proportion of white-winged scoters return to the marine waters of Washington, and if white-winged scoters captured in British Columbia come to Washington the winter after capture, instead of returning to the region of capture. Though the sample size is relatively small, we wanted to evaluate if immigration/ emigration between years occurs. We also compare scoter population trends from the USFWS and 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 the project have now been completed, suggesting confirmation of 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 even some suggestions of differences between different but close flyway subpopulations of white-winged scoters, such as those from the Strait of Georgia and Puget Sound. 2) The time spent by scoters in marine areas is considerable, with 9-10 months for males and 8-9 for females observed, often including molting flightless periods in western Washington in late summer. 3) western Washington contains important wintering and spring staging areas used by white-winged scoters as well as summer molting areas. 4) These staging areas were often different than those used by surf scoters. These Washington spring staging areas also attract a certain proportion of British Columbia white-winged scoters. 5) The white-winged scoters we tracked tended to return daily and yearly often to the same locations, expressing considerable site fidelity. 82 ANNAPOLIS, MARYLAND, USA NOV. 7-11, 2005
SECOND NORTH AMERICAN SEA DUCK CONFERENCE DISTRIBUTION AND CHARACTERISTICS OF WINTER NOCTURNAL RESTING AREAS OF SURF SCOTERS, WHITE-WINGED SCOTERS, IN PUGET SOUND, WASHINGTON STATE Joseph R. Evenson, David R. Nysewander, Thomas A. Cyra, and Bryan L. Murphie Washington Department of Fish & Wildlife; evensjre@dfw.wa.gov The diurnal distribution of wintering marine birds in Puget Sound has been well documented (Nysewander et al. 2004), however, their nocturnal distribution is poorly understood; there is also little data documenting this throughout North America. VHF and satellite telemetry were used to identify nocturnal resting locations of surf (Melanitta perspicillata) and white-winged scoters (Melanitta fusca) in three regions of the greater Puget Sound, Washington State. After nocturnal locations were identified, vessel trips were conducted, using radar and VHF telemetry, to locate the flocks and attempt to determine species composition, flock size, and characteristics of the flocks. Scoters distributed over a wide area would congregate during nocturnal hours in resting flocks. These nocturnal flocks generally occurred in more open/exposed waters, had higher densities, and were more spatially confined than observed during diurnal hours. Nocturnal flocks also occurred in areas that typically have much lower densities during diurnal hours, and were generally centrally located near diurnal foraging areas. Nocturnal resting flocks consisted of both mixed, and segregated species. Mixed flocks included goldeneyes (Bucephala clangula), bufflehead (Bucephala albeola), mergansers (Mergus merganser), loons (Gavia immer), gulls, and horned (Podiceps aurtius) and red-necked grebes (Podiceps grisegena). Distance traveled from diurnal to nocturnal areas ranged from
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