Where do Palearctic migratory birds overwinter in Africa ?

annual migration of millions of birds world-wide has enchanted humans for centuries. Some 200 species breeding in the Palearctic region migrate in numbers of an estimated 3000-5000 millions to their African wintering grounds (Moreau 1972, Curry-Lindahl 1981). Due to the work of scientists in conjunction with information gathered by thousands of bird-watchers and bird-ringers, we know today the principal migratory routes through Europe and the Mediterranean (Alerstam 1990, Berthold 1993). We also understand the flight mechanics (Pennycuick 1989) and the principal physiological regulators of avian migration and orientation (Gwinner 1990, Berthold 1996). However, we still have a lot to learn about the causes of the significant variation in migration among species, populations, age groups and sexes, i.e. the ecological and evolutionary bases of migration as well as the physiology of migration. The European Science Foundation, supported by science-funding agencies in 13 different countries (including Denmark), has provided significant funds for the programme Optimality in Bird Migration. This project uniquely combines the efforts of more than a dozen research groups across Europe (including the Zoological Museum, University of Copenhagen), working on the same set of hypotheses from different angles (for more information, see http://www.esf.org/esf_article.php? language=0& article=92&domain=3&activity=1). Another area where knowledge is still fragmentary concerns the geographical distribution of Palearctic migrants in Africa. For many species, our knowledge may be as superficial as the statement "occurs in eastern Africa" (Rahbek & Madsen 1999) or the necessarily oversimplified range maps in the otherwise impressive Birds of Africa series (Brown et al. 1982, Urban et al. 1986, Fry et al. 1988, Keith et al. 1992, Urban et al. 1997, Fry et al. 2000). For proper scientific analysis, and for conservation management, the spatial resolution is clearly not sufficient. The need to map the distribution of Palearctic migratory birds in Africa So far, we know very little about the geographical location of flyways, stop-over sites, and wintering areas, or the seasonal movements between wintering areas. We know even less about where, for example, the Danish populations of various species occur in Africa compared to populations of the same species from other regions in Europe; we are convinced, however, that significant geographical patterns are yet to be revealed. While we have detailed knowledge about the distribution of migratory birds in Europe (e.g. Cramp 1998), the same detailed information is simply not available for Africa. However, such information is essential for the successful conservation of Palearctic migratory birds which are essentially African and European birds. This situation should basically be regarded as unacceptable. We simply need to know where migratory birds overwinter in Africa. The information that do exist on the distribution of migratory species in Africa is widely scattered, and much is hidden in the "grey literature" or remains to be published. Two organizations have recently put much effort into collecting some of this information and using it to improve conservation decisions. Wetlands International (http://www.wetlands.agro.nl/) has organized the annual International Waterfowl Census, has published several wetland inventories, and is working to protect important wetland sites through the Ramsar Convention and other conservation programs. It is working in close association with BirdLife International (http://www.birdlife.org.uk/) in the effort to establish a global network of Important Bird Areas (IBAs) which are critical sites for conservation of birds at a global, regional or subregional level. Of the African IBAs some have been chosen because of their importance for migratory birds, mainly on the basis of data for non-passerines (e.g. Zalles & Bildstein 2000). 4 Palearctic migrants in Africa