2. Concentrations and Movements of Waterbirds with Potential to Spread Avian Influenza
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2. Concentrations and movements of waterbirds with potential to spread Avian Influenza 2.1 Introduction 2.1.1 Waterbird numbers, distribution and key sites The International Waterbird Census (IWC), Coordinated by Wetlands International and its predecessor organization, IWRB, was established in Europe and West Asia in 1967 and in Africa in 1990. Every year in January, over 20 million waterbirds are counted in the Western Palearctic, and up to 10 million in Subsaharan Africa by a network of about 14,000 largely voluntary waterbird counters (Gilissen et al. 2002, Dodman & Diagana 2003). The use of standardized methods and recording forms and modern computer software ensures that a continental-scale time series of data on waterbird numbers, distribution and population trends is available as the scientific basis of waterbird conservation (e.g. Wetlands International 2002, 2005 Delany et al. 2005). Counts are conducted in January because this is when many waterbird species congregate conspicuously at a relatively small number of sites where they can be readily counted. The January count is supplemented in Subsaharan Africa by a second annual count in July, and there are plans for additional counts throughout Europe, Africa and Asia, in March-April and September-October, to collect information from sites important during migration. 2.1.2 Interpretation of IWC data More than 100 countries now participate in IWC around the world. The Census is coordinated at National Level by a wide variety of organisations and institutes and there are differences in approach which should be borne in mind when interpreting the resulting count data. The census is site-based, and defining sites in a standard way is problematic. Conservation policy uses criteria such as “sites that have held more then 20,000 waterbirds” or “sites that have held more than 1% of a waterbird population”, but criteria for defining sites are rather general and open to interpretation. In this report, many tables are presented which show sites where high numbers of waterbirds have been counted. It should be remembered when using these tables that site definition procedures are not totally objective. An example of this is the Inner Niger Delta in Mali, a wetland whose size varies according to flood conditions, but is, in some seasons, approaching the size of a small European country such as The Netherlands. For the purposes of the Census, this site has been divided into numerous quadrats, and data are presented on this basis, although treating the entire area as one very large “site” might be justified. It should also be borne in mind that IWC totals are nearly always under-estimates of actual numbers of birds present in a site or a country. No country can cover 100% of suitable habitat, and site-based methods do not allow meaningful extrapolation. The IWC 23 totals are thus affected by levels of count coverage achieved at each site and in each country. Great efforts are made to standardise coverage from year to year, and most European countries now achieve high levels of coverage every year. Coverage in West Asia and Africa is less complete, but the most important sites in most countries have been covered between 1990 and 2005, the period covered by this report. 2.1.3 Final list of Higher Risk species for which detailed analyses were undertaken For detailed analysis of numbers, distribution and movements 15 of the 25 “Higher Risk” species identified in Table 1.1 above were selected for analysis, plus two of the “near- selected” species also identified in Chapter 1. The final list of species selected for these analyses is as follows: Mute Swan Cygnus olor Greater White-fronted Goose Anser albifrons Greylag Goose Anser anser Red-breasted Goose Branta ruficollis Eurasian Wigeon Anas penelope Gadwall (“near-selected”) Anas strepera Common Teal Anas crecca Mallard Anas platyrhynchos Northern Pintail Anas acuta Garganey Anas querquedula Northern Shoveler Anas clypeata Red-crested Pochard Netta rufina Common Pochard Aythya ferina Tufted Duck Aythya fuligula Northern Lapwing Vanellus vanellus Black-headed Gull Larus ridibundus Black Tern (“near-selected”) Chlidonias niger It was agreed that with the time available for this “preliminary analysis” it would be possible to undertake detailed analyses of numbers, key sites and movements of about 15 species. Species from the final list of “Higher Risk” species identified above on the basis of their habitat use, gregariousness and degree of mixing were not included if data quality were considered to be relatively poor, or if the data were in a form which could not be readily analysed. The waterbird count data for geese are collected, stored and analysed separately from the rest of the International Waterbird Census database, and for this reason, only three of the geese were included. Similarly, the count data for most species of gull are incomplete and Larus canus was excluded for this reason. The geese included were the two most widespread in Europe ( Anser albifrons and Anser anser ) which make extensive use of farmland, plus a scarce species ( Branta ruficollis ) an individual of which 24 died of HPAI in Greece in 2005. Cygnus columbianus and Marmaronetta angustirostris were excluded because of their scarcity and their restricted distributions in Europe. Finally, waders (shorebirds) may be less susceptible to HPAI than Anseriformes, gulls and terns, and Eurasian Golden Plover, Ruff and Black-tailed Godwit were excluded for this reason, leaving one species, Vanellus vanellus to represent this group. Two species, Gadwall Anas strepera and Black Tern Chlidonias niger were included in detailed analyses although they only qualify as “near-selected” in the analysis undertaken in Chapter 1. Gadwall is the one widespread European dabbling duck otherwise excluded, and Black Tern has a more extensive non-breeding range in Africa than any other Higher Risk species. 2.1.4 The count data presented The analyses presented in this report have been undertaken on behalf of the European Commission, specifically as an “urgent preliminary assessment”. The best available data have been used to summarise numbers, distribution and movements of 17 species considered to present a High Risk of spreading Avian Influenza. The data presented for some species, particularly the geese, Northern Lapwing, and Black-headed Gull, were collected from a less standardised set of sites than those for other species, because of the particular way these species use the landscape (geese, which feed in fields by day and roost at wetlands at night), and because of differences in approach for different taxa in some countries (data for waders are submitted separately in The Netherlands, counting of gulls remains optional in some countries). Waterbird count data presented in this chapter are thus biased towards counts made in the month of January, because of the implementation of IWC as the “midwinter census”. Additional information on important breeding, moulting and staging sites in countries of the former Soviet Union has been extracted from the Russian literature (Table 2.1), but a comprehensive literature review of such sites in the rest of the region included in this report has been beyond the scope of contracted work. Table 2.1: Publications in the Russian literature consulted to supplement data from the International Waterbird Census in analyses of important sites for waterbirds. The identification numbers in the table below are the same as those used in the tables of summarised count data to identify sources of information. No. Reference Andreev V.A. 2003. Stopovers of Anseriformes during spring migration in North Dvina delta. In: Management and conservation of waterfowl populations in Northern Eurasia (with special focus on the White Sea-Baltic 1 Flyway). Petrozavodsk, Russia. Pp. 6-8. Artyukhov A.I. 2003. Migration and status of geese in Bryansk region during last 25 years. Management and conservation of waterfowl populations in Northern Eurasia (with special focus on the White Sea-Baltic Flyway). 2 Petrozavodsk, Russia. Pp. 8-9. Avdanin V.O., P.M. Glazov, V.A. Grabovsky & M.G. Sinitsyn. 2005. Principal places of goose concentration during spring migration in Kostroma Region. In: Waterfowl of Northern Eurasia. Third International Symposium 3 Abstracts. Saint-Petersburg. Pp. 7-8. Bragina, T.M. and E.A. Bragin (Eds). 2002. The most important wetlands of North Kazakhstan (Kostanai Oblast and west part of North-Kazakhstan Oblast) . Moscow: Russkiy Universitet Publishers. 156 pp. (In 4 Russian). Buzun V.A. 2005. Short review of waterbird migration and breeding in east part of Finland Bay and on Ladoga 5 Lake. Waterfowl of Northern Eurasia. Pp. 50-53. 25 Djamirzoyev G., G. Magomedov, Yu. Pishvanov & L. Prilutskaya. 2004. Birds of Dagestansky Nature Reserve. 6 Makhachkala. 95 pp. (In Russian) Fokin, S., Kuzyakin, V., Kalchreuter, and Kirby, J.S. 2000. The Garganey in the former USSR. A compilation of 7 life-history information. Wetlands Internationalglobal Series 7, Wageningen, The Netherlands. Frolov V.V., S.A. Korkina, D.V. Gomzin & A.V. Frolov. 2003. Nesting Anseriformes of the Penza Oblast. 8 Casarca N 9. Moscow, pp. 344-361. Gineev A.M., V.P. Belik & B.A. Kazakov. 2002. Russia. Directory of Azov-Black Sea Coastal Wetlands. Kyiv. 9 Wetlands International. 229 p. 10 Gineev, Krivenko 1998 (Wetlands in Russia 1). Gistsov A.P. 2004. Waterbird monitoring in North Caspian Sea in 2003. Kazakhstan Ornithological Newsletter. 11 Almaty, Kazakhstan. Pp. 19-20. Golovnyuk, V.V. 2005. Distribution and numbers of geese in mouth of Upper Taimyra River, Taymyr. 12 Waterfowl of Northern Eurasia. Pp. 86-87. Gordienko N.S. 2001. Current status of swans and geese in the Southern Zauralie (the Chelabinsk region). In: 13 Problems of waterbird study and conservation in Eastern Europe and Northern Eurasia. Moscow, Russia. Gurtovaya E., P. Tolvanen, T. Eskelin, I. Olsen, T. Bragina, T. Aravak, G. Eichhorn, A.