abstracts of oral and poster presentations - Pacific Seabird Group

trophic level were found between males and females or between years. Hatching-year (HY) Common Murres
fed at a higher trophic level than did after-hatching-year (AHY) birds; however, no differences were found
between HY and AHY Thick-billed Murres. Both Thick-billed and Common murres showed a significant
enrichment in birds δ 13 C during the winter months, indicating that foraging locations shifted nearshore as the
winter progressed. Preliminary analysis also suggests that breeding Thick-billed Murres were significantly
enriched in δ 15 N compared with wintering birds.
INTER-YEAR DIETARY VARIATION AT A SEABIRD COMMUNITY REVEALED THROUGH STABLE-
ISOTOPIC MONITORING [Poster]
Allison T. Moody* 1 (allison.moody@ec.gc.ca) and Keith A. Hobson 1,2 ; 1 Biology Department, University of
Saskatchewan, Saskatoon, SK CANADA; 2 Canadian Wildlife Service-Prairie and Northern Region, Saskatoon,
SK CANADA
Arctic ecosystems are vulnerable to human-induced changes such as increases in contaminant levels and
climatic warming. To predict effects of these changes, it is important to understand trophic relationships among
Arctic organisms. We investigated diets within the seabird community (Thick-billed Murres Uria lomvia,
Northern Fulmars Fulmaris glacialis, and Black-legged Kittiwakes Rissa tridactyla) of Prince Leopold Island,
Nunavut, 2000–2003, to determine the consequences of dietary variation on seabird breeding success. Diet was
monitored using stable isotope measurements (ä 13 C, ä 15 N) in blood samples from the three seabird species.
Stable-carbon isotope analysis gives an indication of source of feeding (i.e., inshore vs. pelagic), and a 15 N
analysis provided an indication of trophic level. We determined significant differences in trophic level and
space use among years for all species. Notably, in 2002, the proportion of fish in the diet dropped and the
variance in diet increased. Fewer chicks than average for all species were fledged in 2002, and Thick-billed
Murre chicks were lighter than in other years. The results suggest that 2002 had reduced fish availability,
perhaps as a result of differences in ice conditions in the preceding year.
AT-SEA OCCURRENCE, DISTRIBUTION, AND THREATS TO XANTUS'S MURRELETS IN BRITISH
COLUMBIA AND WASHINGTON [Poster]
Ken H. Morgan 1 (morgank@pac.dfo-mpo.gc.ca), Patrick D. O'Hara 1 ; Lisa T. Ballance 2 , Harry R. Carter 3 ,
Larry B. Spear 4 , and Terry R. Wahl 5 ; 1 Canadian Wildlife Service, Institute of Ocean Sciences, Sidney, BC
CANADA; 2 NOAA Fisheries, Southwest Fisheries Science Center, La Jolla, CA CANADA; 3 5700 Arcadia
Road, Apt. #219, Richmond, BC CANADA; 4 H.T. Harvey & Associates, San Jose, CA USA; 5 Bellingham, WA
USA
Xantus's Murrelet (Synthliboramphus hypoleucus) is a northeast Pacific endemic, ranging from about
23° to 53°N. Although first reported in British Columbia (BC) and Washington (WA) in the 1940s, the
occurrence of the species in territorial waters was not formally recognised until the 1970s. In 1990, there was
only one accepted record for BC, and the provincial status was designated as "Accidental". With the beginning
of pelagic surveys in the 1970s and 1980s in WA and BC (respectively), it became clear that Xantus's Murrelets
regularly occurred in low numbers in offshore waters. We examine the locations of 82 murrelet sightings (181
individuals) recorded during at-sea surveys, 8 of 10 birds caught in driftnets in 1987, and other historical
records. During systematic at-sea surveys, most (~70%) murrelets were encountered in August and September
(range June through October). Although found from the continental shelf (3,000
m), most murrelets occurred in waters over the outer shelf and slope, placing the species at risk from bycatch in
commercial fisheries and from chronic oiling.
REPRODUCTIVE SUCCESS OF BLACK-FOOTED AND LAYSAN ALBATROSSES ON HAWAIIAN
REFUGE ISLANDS
Marie Morin 1 (marie.morin@pcc.edu), Elizabeth Flint 2 , and Maura Naughton 1 ; 1 U. S. Fish and Wildlife
Service, Portland, OR USA; 2 U. S. Fish and Wildlife Service, Honolulu, HI USA
Reproductive success (chicks fledged/eggs laid) and its components, hatching success (eggs
hatched/eggs laid) and fledging success (chicks fledged/eggs hatched), for Laysan (Phoebastria immutabilis)
and Black-footed (Phoebastria nigripes) albatrosses were measured at Midway Atoll (1992–2003), Laysan