Temporal and spatial patterns in the diet of northern fulmars Fulmarus glacialis in the Canadian High Arctic

Abstract

AQUATIC BIOLOGY Aquat Biol Vol. 10: 181–191, 2010 doi: 10.3354/ab00277 Published online August 31 Temporal and spatial patterns in the diet of northern fulmars Fulmarus glacialis in the Canadian High Arctic M. L. Mallory 1, *, N. J. Karnovsky 2 , A. J. Gaston 3 , K. A. Hobson 4 , J. F. Provencher 5 , M. R. Forbes 6 , G. L. Hunt Jr. 7 , T. Byers 8 , T. A. Dick 9 Canadian Wildlife Service, Box 1714, Iqaluit, Nunavut X0A 0H0, Canada Department of Biology, Pomona College, 175 W. 6th St., Claremont, California 91711, USA National Wildlife Research Centre, Environment Canada, Carleton University, Ottawa, Ontario K1A 0H3, Canada Environment Canada, 11 Innovation Blvd., Saskatoon, Saskatchewan SYN 3H5, Canada Department of Biology, University of Victoria, Victoria, British Columbia V8W 3N5, Canada Department of Biology, Carleton University, Ottawa, Ontario K1S 5B6, Canada Department of Ecology and Evolutionary Biology, University of California – Irvine, Irvine, California 92697, USA Byers Environmental Studies, Box 1049, Teulon, Manitoba R0C 3B0, Canada Department of Zoology, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada ABSTRACT: The northern fulmar Fulmarus glacialis is a medium-sized seabird with a broad, circum- polar range in the northern hemisphere, and is the only petrel that inhabits the High Arctic. We used stomach analysis and stable isotopes (δ 15 N, δ 13 C) of muscles to examine the diet of 179 fulmars dur- ing the breeding season at 4 locations in Arctic Canada, to compare diet to those from studies con- ducted in these regions > 2 decades earlier. Across sampling locations, cephalopods, polychaetes and crustaceans dominated dietary remains in fulmars, although there was some regional variation. Both stable isotopes and stomach dissections showed that a seasonal shift in diet occurred in May, after which fulmars fed at a higher trophic level, suggesting a difference in winter/migration diet and breeding season diet. After migration, fulmar digestive organs decreased markedly in size, and by the time chicks were hatching, these organs were still 17 to 39% smaller than their size when birds arrived at the colony. Despite ongoing changes in the marine environment in much of the Arctic due to global warming, recent fulmar diet samples were similar to samples collected in the 1970s and 1980s, except that a higher proportion of recent collections contained fish. KEY WORDS: Arctic · Cephalopod · Crustacean · Procellariiformes · Reproduction Resale or republication not permitted without written consent of the publisher INTRODUCTION Invertebrate and fish fauna vary across oceano- graphic zones in the North Atlantic in response to differing oceanographic conditions, often on small geographic scales (e.g. Karnovsky et al. 2003). Many marine birds are generalist predators that exploit invertebrates and fish (e.g. Woo et al. 2008). Conse- quently, monitoring the diet of marine birds provides a measure of the diversity and availability of different types of organisms in marine food webs and allows detection of shifts in food webs due to changes in oceanographic conditions (e.g. Gaston et al. 2003, Frederiksen et al. 2004, 2006). In the North Atlantic, the northern fulmar Fulmarus glacialis is the only Procellariiform seabird (petrel) found in Boreal, Low Arctic and High Arctic oceano- graphic zones (Salomonsen 1965, Hatch & Nettleship 1998). It feeds on zooplankton, cephalopods, fish and carrion across its range in Boreal and Low Arctic waters (Furness & Todd 1984, Hamer et al. 1997, Phillips et al. 1999, Garthe et al. 2004). Relatively less is known about *Email: mark.mallory@ec.gc.ca © Inter-Research 2010 · www.int-res.com