Working Group on Seabird Ecology (WGSE). ICES CM 2004/C:05 ...

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Gjerdrum, C.G., Vallée, A.M.J., St. Clair, C.C., Bertram, D.F., Ryder, J.L. and Blackburn, G.S. 2003. Tufted puffin reproduction reveals ocean climate variability. Proceedings of the National Academy of Science of the USA, 100: 9377–9382. Harding, A.M.A., Piatt, J.F. and Hamer, K.C. 2003. Breeding ecology of horned puffins (Fratercula corniculata) in Alaska: annual variation and effects of El Niño. Canadian Journal of Zoology, 81: 1004–1013. ICES. 2003. Report of the <strong>Working</strong> <strong>Group</strong> on Seabird Ecology. ICES CM 2003/C:03. Inchausti, P., Guinet, C., Koudil, M., Durbec, J.-P., Barbraud, C., Weimerskirch, H., Cherel, Y., and Jouventin, P. 2003. Inter-annual variability in the breeding performance of seabirds in relation to oceanographic anomalies that affect the Crozet and the Kerguelen sectors of the Southern Ocean. Journal of Avian Biology, 34: 170–176. Jenouvrier, S., Barbraud, C., and Weimerskirch, H. 2003. Effects of climate variability on the temporal population dynamics of southern fulmars. Journal of Animal Ecology, 72: 576–587. Jones, I.L., Hunter, F.M., and Robertson, G.J. 2002. Annual adult survival of least auklets (Aves, Alcidae) varies with large scale climatic conditions in the North Pacific Ocean. Oecologia, 133: 38–44. Oswald, S., Huntley, B., and Hamer, K.C. 2004. Exploring the impact of climate on the distribution of great skuas breeding in the UK. Abstract, 8 th International Seabird <strong>Group</strong> Conference, Aberdeen, 2–4 April 2004. Ramos, J.A., Maul, A.M., Ayrton, V., Bullock, I., Hunter, J., Bowler, J., Castle, G., Mileto, R., and Pacheco, C. 2002. Influence of local and large-scale weather events and timing of breeding on tropical roseate tern reproductive parameters. Marine Ecology Progress Series, 243: 271–279. Schreiber, E.A. 2002. Climate and weather effects on seabirds. In Biology of marine birds. Ed. By Schreiber, E.A. and Burger, J. CRC Press, Boca Raton, Florida: 179–216. Thompson, K.R., and Furness, R.W. 1991. The influence of rainfall and nest site quality on the population dynamics of the Manx shearwater Puffinus puffinus on Rhum. Journal of Zoology, London, 225: 427–437. Thompson, P.M., and Ollason, J.C. 2001. Lagged effects of ocean climate change on fulmar population dynamics. Nature 413: 417–420. 5 A COMPARISON OF SEABIRD COMMUNITIES AND PREY CONSUMPTION IN THE EAST AND WEST NORTH ATLANTIC Term of reference: complete the work carried out in 2003 to compare seabird communities and prey consumption between the east and west North Atlantic. 5.1 Introduction The WGSE 2002 meeting completed a summary of the breeding seabird numbers by species, total seabird energy requirements and approximate food consumption equivalents, in all ICES areas (approximately described as the ‘east North Atlantic’). Given the pronounced differences in seabird community composition and species abundances, and in fish stocks and fisheries, between the west and east North Atlantic, WGSE 2003 thought that it might be instructive to compare and contrast the patterns of seabird community composition and energy requirements between ICES and NAFO areas (approximately ‘east’ and ‘west’ North Atlantic), in relation to broad differences in the histories of fish stocks and fisheries in these areas. We here complete the comparison of the seabird communities and their consumption on both sides of the North Atlantic. The relationships to fish stocks and fisheries need to be followed up. 5.1.1 Population estimates The estimates of numbers presented here are primarily of birds nesting on the coast and feeding wholly or partially at sea, but the numbers of gulls may also include a small fraction of non-marine, inland-breeding segments of the populations. They are based on the input by members of the WGSE who were asked to provide the best estimates of the numbers of seabirds currently breeding in their respective countries. Some of these are now several years old, and predate recent national updates. The background data are presented in earlier WGSE reports. Although a number of known caveats have been considered here, discrepancies from an updated analysis of the database would probably be small. Data from the huge colonies of, e.g., northern fulmars, guillemots, little auks and Atlantic puffins in Canada, Greenland, Iceland, Svalbard and the Barents Sea should not be considered as definitive. Some are quoted as “guesstimates” and await more detailed censuses. Furthermore, while data for many species were presented to the nearest hundred, ten or even individual pairs, others were presented as ranges, some as large as 100,000–1,000,000 pairs. For the sake of simplicity, all such ranges were tabulated as mid-points between the two extremes. 18 ICES WGSE Report 2004
Calculation of numbers of birds in the non-breeding part of population Whereas the numbers of breeding adults were generally known or estimated based on field data, numbers of nestlings and pre-breeders were estimated empirically using a classification of whether the species lay single or multiple-egg clutches, and calculations based numbers of breeding pairs (bp) plus numbers of immatures (calculated for single-egg species = (bp x 0.7) + (bp x 0.7); multi-egg species = (bp x 0.6) + (bp x 1). These estimates assumed that numbers of non-breeding birds (immatures and deferred breeders) were equivalent to 35% or 30% of the breeding population and that the fledging success of single-egg and multi-egg clutch species was 0.7 and 1.0 chicks/pair, respectively (Cairns et al. 1991). These calculations are very crude, and do not take into consideration population trends or life histories of the different species. In the calculations of seasonal changes in total numbers (and hence biomass and food consumption) of birds in a population (i.e., breeding pairs + immatures), the resulting figures have been used for the whole year, and no correction has been made to account for the fact that reproduction takes place during summer and mortality takes place during the year. As a result, the autumn population sizes will be underestimated and spring population sizes will be overestimated. For single-egg species these under- and overestimates will each be about 10%, and for multi-egg species about 20%. Of the many species of divers, ducks and geese, some of which may be equally defined as seabirds as some of the gulls, only the eider duck is included as a breeding species due to its total dependence on the sea for food, and to their very large numbers in some areas. Other waterfowl which breed inland but feed in the sea in large numbers at other times of the year are, however, considered where relevant. Data sources were Anker-Nilssen et al. (2000), Delany and Scott (2002), Durinck et al. (1994), Gilchrist (pers. com.), Gilliland (pers.com.), Hagemeijer and Blair (1997), Kershaw and Cranswick (2003) Merkel et al. (2002), Mosbech and Boertmann (1999), Nygård et al. (1988) and Savard (pers.com.). At the other end of the scale, some rare species whose total numbers do not total more than a few hundred (e.g., gullbilled tern, Sabine’s gull) are not included in the calculations. In addition to birds that breed in specific ICES and NAFO areas, there are, at times, large numbers that breed outside the areas but are present at certain times of the year as migratory or wintering populations. Furthermore birds breeding within the ICES and NAFO areas may also move to other areas during migration or to spend the winter. We have attempted to account for these movements by estimating the occurrence by month for each species in each subarea and making rough estimates of the numbers of individuals present. The resulting numbers were summed by season by dividing the year into four quarters. The summer season in ICES and NAFO was chosen separately so the summer included all the species breeding seasons as far as possible. The resulting seasons differed by two month between ICES and NAFO because of the climatic and hence phenological diffences. In the ICES region winter was defined as Nov- Jan, spring Feb-Apr, summer May-July and autumn Aug-Oct. In NAFO, winter was defined as Jan-Mar, spring Apr- June, summer July-Sep and autumn Oct-Dec. Migration tendency and routes of the various species in ICES areas were taken from Anker-Nilssen et al. (2000), Bakken et al. (2003), Lyngs (2003), Petersen (1982), and Wernham et al. (2002). These estimates were limited to the commonest species breeding within a given area, i.e., species whose biomass constituted > 2% of the original estimate of the total biomass of seabirds breeding in that area (based on Tables 2.1–2.5, ICES 2002). For NAFO, the seasonal movements of seabirds are based mainly on Diamond et al. (1993), Huettmann (pers. com.) and Lyngs (2003). 5.1.2 Consumption The annual consumption by seabirds in a given area was estimated using calculated species-specific energy demands, numbers of individuals of that species within that area, number of days present and a mean energy density of food set at 5.5 kJ/g (see box below). Like the calculations of bird numbers, this was modelled separately for the four seasons and summed for the year. Daily and hence seasonal energy demands were calculated using the methods described in Barrett et al. (2002) – see box below. ICES WGSE Report 2004 19
Page 1 and 2: ICES Oceanography Committee ICES CM
Page 3 and 4: Contents 1 Introduction............
Page 5 and 6: 1 INTRODUCTION 1.1 Participation Th
Page 7 and 8: egion, but its size and importance
Page 9 and 10: addition, mass mortality events on
Page 11 and 12: During autumn migration surprisingl
Page 13 and 14: Table 3.4.1. Score of the nine vuln
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Page 17: performance and climatic variables,
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Page 25 and 26: Table 5.8. Approximate food consump
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Page 29 and 30: 6 CONSUMPTION OF PREY BY SEABIRDS I
Page 31 and 32: WGSE and ACE recommended in 2003 (I
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Page 35 and 36: Kittiwake breeding success at Foula
Page 37 and 38: 7.7 Seabird population trends as an
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Page 41 and 42: Table 8.2. Some breeding population
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Page 45 and 46: Table 8.5. Continued. HUNTING STATU
Page 47 and 48: Norwegian Institute for Nature Rese
Page 49 and 50: 10 ANNEXES Annex 1 List of particip
Page 51 and 52: Relation to strategic plan: Resourc
Page 53: English name Scientific name Goosan

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