abstracts of oral and poster presentations - Pacific Seabird Group

POST BREEDING MOVEMENTS AND HABITATS OF THE BLACK-FOOTED ALBATROSS [Poster]
K. David Hyrenbach 1 (khyrenba@duke.edu), Cheryl Baduini 2 , Michelle Hester 3 Carol Keiper 3 , and Josh
Adams 4 ; 1 Duke University Marine Lab, Beaufort, NC USA; 2 Claremont Colleges, Claremont, CA USA;
3 Oikonos Ecosystem Knowledge, Bolinas, CA USA; 4 U.S. Geological Survey, Vallejo, CA USA
The Black-footed Albatross (Phoebastria nigripes) is susceptible to bycatch in domestic and foreign
longline fisheries across the North Pacific Ocean. While large population declines have been projected using
fishing effort and bycatch estimates, very little is known about the movements and threats faced by individual
albatrosses at-sea, especially during their post-breeding dispersal. To investigate Black-footed Albatross
distribution, habitat-use, and overlap with longline fisheries, we tracked the movements of nine birds (4 females
and 5 males) using 54-g ARGOS transmitters. The birds were caught at-sea within the Cordell Bank National
Marine Sanctuary, off central California, and tracked from July to October 2004. We obtained location data for
an average of 45 days (range 34–58 d for 5 continuous tags; 32–58 d for 4 tags on 24 hr on/24 hr off duty cycle).
Seven of the tracked individuals departed Cordell Bank in a southwest direction and then looped back towards
northern latitudes (45–50°N), with the other two birds remaining farther south (20–30°N). All of the satellitetracked
birds ventured beyond the US Exclusive Economic Zone, with three of them traveling west of the
International Dateline. Our results suggest that post-breeding Black-footed Albatrosses do not remain within
sanctuary waters but instead range widely across areas targeted by pelagic longline fisheries.
CLIMATE CHANGE AND MURRES: A CIRCUMPOLAR SEESAW
David B. Irons 1 (david_irons@fws.gov), Tycho Anker-Nilssen, Anthony J. Gaston, G. Vernon Byrd, Knud Falk,
Grant Gilchrist, Martti Hario, Måns Hjernquis, Yuri V. Krasnov, Anders Mosbech, Jim Reid, Greg Robertson,
Bergur Olsen, Aevar Petersen, Hallvard Strom, and Kenton D. Wohl 1 ; 1 U. S. Fish and Wildlife Service,
Anchorage, AK USA
Data on murre population trends from 52 colonies, involving more than 490 colony-years, from around
the world were brought together for a circumpolar perspective of the effects of climate change on seabird
populations. Circumpolar changes in Common and Thick-billed murre populations over the past 25 years were
associated with decadal shifts of northern hemisphere atmospheric oscillations, the Pacific Decadal Oscillation
and the North Atlantic Oscillation. These oscillations are correlated with decadal changes in ocean
temperatures. The long-term sea surface temperature (SST) trends in the northeast Atlantic and the northeast
Pacific mirrored each other resulting in a “seesaw” effect. When the northeast Atlantic cooled, the northeast
Pacific warmed, and vice versa. Murre populations were in a constant flux: when SST shifted slightly
(~0.5°C),
murre populations declined. The two species reacted somewhat differently to SST shifts. Thick-billed Murres,
the arctic-adapted species, did better when the SST increased slightly, and the more temperate Common Murre
did better when the SST decreased slightly.
SITE FIDELITY AND THE DEMOGRAPHIC IMPLICATIONS OF WINTER MOVEMENTS BY A
MIGRATORY BIRD: THE HARLEQUIN DUCK
Sam Iverson (siverson@sfu.ca) and Dan Esler; Centre for Wildlife Ecology, Simon Fraser University,
Burnaby, BC CANADA
Understanding the degree of demographic connectivity among population segments is central to the
fields of population ecology and conservation biology. However, delineating demographically discrete
population units has proven challenging, particularly for migratory birds. We used radio-telemetry to document
winter site fidelity, movement patterns, and the spatial scale of demographic independence of Harlequin Ducks
(Histrionicus histrionicus) in Prince William Sound, Alaska. During the winters of 1995–1996 through 1997–
1998 and 2000–2001 through 2002–2003, 434 females were implanted with transmitters and their signals
tracked from aircraft. Using a spatially nested design, we determined that 75% of radioed females remained in
the bay or coastline area (mean area ± SE = 16.7 ± 1.5 km 2 ) where they were originally trapped, 94% remained
on the same island or mainland region within Prince William Sound (127.5 ± 39.1 km 2 ), and fewer than 2%
emigrated from the 4,500-km 2 study area as a whole. Estimates for population size, survival, and movement
rates were incorporated into a demographic model, the results of which indicated immigrant females accounted