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

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Table 8.5. The availability of time series data of life history parameters of seabird populations in the North Sea. Parameter Availability Reference example Populations - breeding population size +++ Mavor, R.A., Pickerell, G., Heubeck, M., and Mitchell, P.I. 2002. Seabird numbers and breeding success in Britain and Ireland, 2001. Joint Nature Conservation Committee, Peterborough (UK Nature Conservation No. 26.) Breeding population size (numbers of pairs or occupied nests) is probably the most widely available parameter and there is often a legal requirement to collect such data for species of conservation concern. However, monitoring seabird breeding numbers alone, will not only fail to provide any indication as to the cause of a measured change in numbers, but also may present a less than optimal approach to detecting change, since specific life history parameters may vary more strongly in response to changes in food supply than would breeding numbers. Detailed time series exist for British seabird colonies from 1986–2004. For a few species and specific colonies, time series exist for 1900–2004 on a decadal basis and in some cases an annual basis. - incidence of non-breeding + Harris M.P., Wanless S., and Rothery P. 1986. Counts of breeding and non-breeding Guillemots Uria aalge at a colony during the chick rearing period. Seabird, 9: 43–46. Seabirds may forego breeding in years of low prey abundance and as such this parameter is an indicator of the state of environmental conditions prior to the breeding season. A few time series may exist but are not readily available. - adult survival ++ Ratcliffe N., Catry P., Hamer K.C., Klomp N.I., and Furness R.W. 2002. The effect of age and year on the survival of breeding adult Great Skuas Catharacta skua in Shetland. Ibis, 144: 384–392. In general, seabirds represent extreme K-selected species, in which adult survival is generally high, and annual reproductive output low. A significant reduction in adult survival by causes a stronger response of population size than a change in most other parameters. Several time series exist, mostly for about 1985–2004. - recruitment % of cohorts that recruit + Becker P.H., H. Wendeln, and J. González-Solis 2001. Population dynamics, - recruitment, individual quality and reproductive strategies in Common Terns Sterna hirundo marked with transponders. Ardea, 89: 241–252. Juvenile mortality is in most species quite substantial and relatively few juveniles recruit into the breeding population. Fluctuations in juvenile mortality may result from poor fledging condition or adverse environmental conditions after the breeding season. Recruitment rates into breeding populations (rejuvenating the breeding stock) indicate survival of young birds and as it were “overwintering” success. In many long-lived seabirds, recruitment into the breeding population takes place after several years (up to 12 years in some species). A relatively minor or at best a delayed response might be expected of population size. A few time series exist for about 1990–2004. - recruitment age + Frederiksen, M., and T. Bregnballe. 2001. Conspecific reproductive success affects age of recruitment in a great cormorant Phalacrocorax carbo sinensis colony. - Proceedings of the Royal Society of London, series B, 268: 1519–1526. In many long-lived seabirds, recruitment into the breeding population takes place after several years (up to 12 years in some species). Shifts in recruitment age may point at density dependent changes in the likelihood prospecting young birds can enter the population. Annual recruitment rates into the breeding population may indicate the quality of the colony and year in terms of, e.g., food supply. Some data exist, but may not provide complete time series. - immigration rate + Moss R., Wanless S., and Harris M.P. 2002. How small Northern Gannet colonies grow faster than big ones. Waterbirds, 25: 442– 448. The scope for immigration into established breeding colonies may result from density dependent mechanisms influenced by for example per capita food supply and available nesting space. Some data exist, and there may be some time series, but often based on modelling rather than purely empirical data. - per capita emigration rate + Frederiksen M., and Petersen A. 2000. The importance of natal dispersal in a colonial seabird, the Black Guillemot Cepphus grylle. Ibis, 142: 48–57. The need to emigrate out of an established breeding colony may result from density dependent mechanisms influenced by for example poor food supply and predation rates. Modelling can be used to estimate these rates for certain well studied colonies. 44 ICES WGSE Report 2004
Table 8.5. Continued. HUNTING STATUS +++ Spaans A.L. 1998. Breeding Lesser Black-backed Gulls Larus graellsii in The Netherlands during the 20 th century. Sula, 12: 173– 182. The most marked changes in seabird populations in the North Sea over the past 150 years have resulted from the relaxation of harvesting (seabirds as food), hunting (sports, food), and persecution (seabirds as pests). These impacts, summarised as ‘hunting status’ may well mask environmental factors that impact seabird populations. Knowledge of statutory protection and periods of persecution are generally well known since 1900. Reproduction and food provisioning - reproductive success +++ Mavor, R.A., Pickerell, G., Heubeck, M., and Mitchell, P.I. 2002. Seabird numbers and breeding success in Britain and Ireland, 2001. Joint Nature Conservation Committee, Peterborough (UK Nature Conservation No. 26.). Breeding success can be measured in various ways and substantial data are collected over a wide range of species (numerous colonies, study plots) for at least several decades. Success can be measured in various ways, not detailed here, and is indicative of breeding conditions and food supply. Detailed data exist as time series for many colonies since 1986, and for a few species and colonies for earlier decades. - laying date ++ Greenwood, J.J.D. 1983. The laying date of Razorbills Alca torda. Ibis, 124: 108. Laying is usually timed such that chicks are to be fed when food supply is at its maximum. Short summer seasons (e.g., at high latitudes) lead to shorter windows). As early as possible breeding is often advantageous and changes in laying dates may result from climatic fluctuations. Time series exist for certain species and colonies for probably several decades. - clutch size ++ Bolton M., Monaghan P., and Houston D.C. 1993. Proximate determination of clutch size in lesser black-backed gulls: the roles of food supply and body condition. Canadian Journal of Zoology, 71: 273–279. Favourable breeding conditions will lead to a maximal clutch size, poor conditions may give rise to smaller clutches. Note that many seabirds lay only a single egg per season. Time series exist for certain species and colonies for probably several decades. - egg size ++ Furness R.W. 1984. Influences of adult age and experience, nest location, clutch size and laying date on the breeding success of the Great Skua Catharacta skua. Journal of Zoology, 202: 565–576. High quality parents produce better and larger eggs than conspecifics of less individual quality. Favourable breeding conditions permit birds to produce better (larger) eggs. Time series exist for certain species and colonies for probably several decades. - chick growth rate ++ Drent R.H., Klaassen, M., and Zwaan B. 1992. Predictive growth budgets in terns and gulls. In Population dynamics of Lari in relation to food resources. Ed. by Spaans A.L. Ardea 80: 5–17. Favourable breeding conditions (e.g., abundant food supply) make chicks grow better. Time series exist for certain species and colonies for some years, but rarely over several decades. - mass of fledglings ++ Barrett, R.T., and Rikardsen, F. 1992. Chick growth, fledging periods and adult mass loss of Atlantic Puffins Fratercula arctica during years of prolonged food stress. Colonial Waterbirds, 15: 24– 32. Body mass at fledging may be considered an indicator of favourable growth. Time series exist for certain species and colonies for some years, but rarely over several decades. - adult nest and brood attendance; provisioning rate + Coulson, J.C., and Johnson, M.P. 1993. The attendance and absence of adult Kittiwakes Rissa tridactyla from the nest site during the chick stage. Ibis, 135: 372–378. Poor food supplies during breeding lead to prolonged absences of parent birds at the nest and to low provisioning rates. Time series exist for certain species and colonies for some years, but rarely over several decades. BODY CONDITION OF BREEDERS + Wendeln, H. 1997. Body mass of female Common Terns (Sterna hirundo) during courtship: relationships to male quality, egg mass, diet, laying date and age. Colonial Waterbirds 20: 235–243. The body condition of breeding birds is an indicator of both quality of the bird and the conditions it is breeding in. Data sets are limited for most species and there are few monitoring programmes available. Time series exist for certain species and colonies but data are mostly just for some years. ICES WGSE Report 2004 45
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
Page 15 and 16: It might be considered useful to di
Page 17 and 18: performance and climatic variables,
Page 19 and 20: Calculation of numbers of birds in
Page 21 and 22: Table 5.1. Relative species composi
Page 23 and 24: Table 5.4. Approximate numbers of s
Page 25 and 26: Table 5.8. Approximate food consump
Page 27 and 28: Kershaw, M., and Cranswick, P.A. 20
Page 29 and 30: 6 CONSUMPTION OF PREY BY SEABIRDS I
Page 31 and 32: WGSE and ACE recommended in 2003 (I
Page 33 and 34: The present level is that around 60
Page 35 and 36: Kittiwake breeding success at Foula
Page 37 and 38: 7.7 Seabird population trends as an
Page 39 and 40: 8.2.1 UK (ICES IVa-c) Data on popul
Page 41 and 42: Table 8.2. Some breeding population
Page 43: Table 8.4. Some breeding population
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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