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EURING Newsletter - Volume 3 - July 2001 THE BRITISH AND IRISH MIGRATION ATLAS NEARS COMPLETION! by British Trust for Ornithology (BTO) BRITISH TRUST
FOR ORNITHOLOGY As you read this, the team at the British Trust for Ornithology (BTO) should be putting the final touches to the manuscript of their forthcoming book, The Migration Atlas: Movements of the Birds of Britain and Ireland. This ambitious project, that has been carried out over the last four years, will be an important milestone for presenting the results of ringing in Britain and Ireland since 1909. The book is due to be published by T& A D Poyser at the end of 2001. The main part of the book consists of 188 species accounts. Every species present in Britain & Ireland at sometime during the year for which we have sufficient ring-recoveries to provide information on movements will be covered. For each of these species, we carried out a standard set of mapping and analyses of movement patterns, with funding from the Heritage Lottery Fund, ringers, BTO members and commercial/charitable trust sponsorship. The analyses included both the recoveries of birds ringed in Britain and Ireland, and those of birds ringed abroad and recovered in Britain or Ireland. The results of our analyses were sent to voluntary authors, for them to write the species accounts. These are a mixture of professional and amateur ornithologists but all experts on their allocated species. In each species account, the author brings together information from the ring-recoveries and from other sources (such as through-the-year distribution data, data from bird observatories, at-sea survey data for seabirds) to provide a clear interpretation of the movements undertaken by their species throughout the year. Wherever possible, authors have also included the results from intensive field studies of movements, such as colour-marking work and remote-tracking using satellites, all of which add exciting supplementary information to that which can be obtained from metal ringing. All species are included if they have enough ring-recoveries, whether they are long-distance or trans-Saharan migrants (eg Puffinus puffinus, Hirundo rustica), partial migrants (eg Carduelis carduelis) or traditionally 'dispersive' (eg Rissa tridactyla) or even sedentary (eg Cepphus grylle, Passer domesticus) in Britain & Ireland. For each of these species, the book will contain a first page, with information that is presented in a standard way for all species (eg locations where recovered birds have been ringed, age and month of ringing, numbers ringed and recovered, finding circumstances and so on). There will then be the text and a number of maps, the length and number depending on the complexity of the species' movements. As well as the main species texts, there will be a number of supporting chapters. There is an introduction to methods of studying bird movements and a chapter on the Ringing Scheme in Britain and Ireland. There is a chapter of detailed methods, to accompany the texts and maps. There is also a chapter highlighting the important results from some detailed across-species statistical analyses that have been carried out, lead by Gavin Siriwardena. These look at the degree of migrancy exhibited by each species, and differences in movement patterns between different age classes, sexes and birds from different regional sub-populations within Britain & Ireland. The results of these analyses are also highlighted in the individual species texts and given in detailed appendices at the back of the book. A further chapter, importantly, deals with the ecology and physiology of migration, expertly written by Peter Evans and Franz Bairlein, and with the influence of weather on movements, compiled by Norman Elkins. This chapter can only be a summary of the huge amount of information available but gives a very important overview and key references to guide the reader to further material of interest. The Migration Atlas project has been an important 'stock-taking' exercise for us all, so it is equally important that the book will contain chapters summarising the importance for bird conservation of the movement patterns identified and where the gaps in our knowledge still lie. A series of recommendations will state possible ways in which we can fill the gaps in knowledge in future, both through ringing and by other methods (such as exciting new developments in remote tracking technologies). The new Atlas will be of great value for conservation and an invaluable reference source for ornithologists, conservation organisations and policy-makers. It will highlight the importance of Britain and Ireland as the wintering area for breeding birds from much further afield, such as for Golden Plovers (Pluvialis apricaria) from Iceland (Map 1), Turnstones (Arenaria interpres) from both Greenland/Canada and Fennoscandia (Map 2) and Black-headed Gulls (Larus ridibundus) from right across continental Europe (Map 3). It will show both established migration routes, for species such as Barnacle Goose (Branta leucopsis), and provide new insights into the seasonal influxes into Britain & Ireland of populations from continental Europe, such as Greater Black-backed Gulls (Larus marinus), Greenfinches (Carduelis chloris) and Starlings (Sturnus vulgaris). The book will also show where British and Irish breeding birds spend the winter months, and therefore where we should look for threats to their populations outside the breeding season. Of course previous work has already shown that problems in wintering areas have affected the birds breeding in Britain and Ireland, such as droughts in the Sahel reducing the over-winter survival of trans-Saharan migrants like Whitethroat (Sylvia communis) and Sedge Warbler (Acrocephalus schoenobaenus), and the capture of large numbers of terns (Sterna spp) for food or bait off the coasts of West Africa. All these previous results will feature in the book, along with many new ideas about conservation issues for each species. For example, ringing shows that the Ring Ouzels (Turdus torquatus) that breed in Britain spend the winter in Iberia and in the highlands of North Africa, notably Morocco's Atlas Mountains (Map 4). British Ring Ouzels have been placed on the Amber List of Birds of Conservation Concern (moderate concern), mainly because of a large decline in their breeding range in Britain during the last 25 years. Ian Burfield, a student at Cambridge University, is studying the reasons behind the population changes, and is also the author for the Migration Atlas species account. He has used both British and other European ring-recoveries (mainly from Scandinavia, with many thanks to those ringing schemes involved) to show that the wintering areas of these different populations seem to overlap. As the Scandinavian populations of Ring Ouzel seem to be fairing OK, these preliminary results suggest that the threats to British birds are not coming from the wintering areas. Ian is doing fieldwork in an attempt to find out whether the problems lie on the breeding grounds. It is possible that threats exist on the migration route for the British birds, or that the wintering altitudes of the different populations vary, and these ideas will also need further investigation. Each time we read one of the new species accounts for the Migration Atlas we find ideas for further research on migration that needs to be carried out, either by new ringing projects or by other methods. In this respect, the publication of our Migration Atlas will be incredibly important in developing plans for further migration research, hopefully in close collaboration with our colleagues in mainland Europe. The concluding 'conservation implications' and 'recommendations' chapters will be very important in showing what we need to do to improve our knowledge of bird movements in the future. The British and Irish Migration Atlas project has used ring-recovery data gathered between 1909 and 1997. But it is now a new millennium, and the ringing that is continuing across Europe now, in more and more countries, is already providing the basis for understanding the remaining unknowns in bird migration, as well as for monitoring possible changes to migration routes, breeding, wintering and staging areas (eg as a result of global climate change?). Let us hope that the publication of our book, dealing with only a very small part of Europe, along with those from other European Ringing Schemes already produced or in production at the moment, will provide the incentives for the next steps. These should be Europe-wide atlases, and more and more collaborative work across Europe to find out about the movements of our birds and provide better scientific knowledge on which to base their improved conservation. Map 1 - Exchanges of ringed Golden Plover (Pluvialis apricaria) showing the importance of Britain and Ireland as a wintering area for birds from the Icelandic breeding population.
Map 2 - Recoveries in the breeding season (solid lines) and winter (dotted lines) of Turnstones (Arenaria interpres) present in Britain or Ireland during autumn. Birds from both the Canada/Greenland and the Fennoscandian breeding populations visit Britain & Ireland in autumn. Many stay for the winter while others move on to winter in Africa.
Map 3 - Locations abroad during the breeding season of Black-headed Gulls (Larus ridibundus) present in Britain or Ireland during the winter, showing how important Britain and Ireland are for populations breeding further north and east in mainland Europe, and in Iceland.
Map 4 - Wintering locations of Ring Ouzels (Turdus torquatus) that were present in Britain during the breeding season. British birds spend the winter mainly in Iberia and Morocco, as do those from Scandinavia.
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