Voorkant omslag LivingSummary on of the edge: Wetlands and birds in a changing Sahel LivingSummary on of the edge: Wetlands and birds in a changing Sahel About the importance of the Sahel as wintering area of European migratory bird species ISBN 978-90-79341-03-0 This brochure is written on request of the Dutch Centre for Water Management of Rijkswaterstaat. It gives a summary of Living on the edge: Wetlands and birds in a changing Sahel Leo Zwarts, Rob G. Bijlsma, Jan van der Kamp, Eddy Wymenga (2009). KNNV Publishing, Zeist. 564 pag. ISBN 978-90-5011-280-2. To order see www.knnvpublishing.nl. The graphs and maps (Dick Visser), water colours (Jos Zwarts) and photos (Floris Deodatus, Nicolas Gaidet, Hans Hut, Ben Koks, Benny Klazenga, Jan van de Kam, Wim Mullié, Gray Tappan, Leo Zwarts) are all taken from the same book. The references are given in Living on the edge. There is also a French and Dutch edition of this brochure; “Résumé français de Living on the edge: wet- lands and birds in a changing Sahel (ISBN 978-90-7934-104-7) and “Nederlandse samenvatting van Living on the edge: wetlands and birds in a changing Sahel” (ISBN 978-90-5011-280-3). Layout and printing: Brandsma Offset Ferwerd. Contents Billions of birds from Eurasia spend the northern winter in Afrika....................................................................................................3 Migratory birds connect continents Europe’s long-distance migrants are in decline Where do our migrants spend the winter in Africa? Changes in the Sahel..........................................................................7 Rainfall Rivers and wetlands Long-term changes The decline of wetlands Summary Population trends in Sahel migrants.........................................21 Winter mortality in dry years The impact of Sahel conditions on return migration and breeding performance Population declines after dry Sahel years Continuous decline Are numbers of long-distance migrants governed by conditions in the breeding or in the wintering areas? Why some long-distance migrants show an increase Year-round protection of migratory bird species................28 Effective bird protection in the Sahel Effective protection of long-distance migrants in Europe Billions of birds from Eurasia spend the northern winter in Africa In the summer of 1969, sharp-witted distance migrants with conditions in the birders in various parts of Europe were African wintering areas is now within our struck by the scarcity of Common grasp, especially relevant because so many Whitethroats on the breeding grounds. long-distance are in rampant decline. If ups Remember: this was the era that stan- and downs of ‘our’ migrants are mainly dardised monitoring of breeding birds triggered by events occurring in the Afri- was still in its infancy (in Britain, and can wintering areas, (better) protection in nowhere else). To be noticed on such a the breeding areas will not improve the scale, the decline must therefore have fortunes of this group of birds. A legiti- been enormous, as it turned out to be. mate question therefore is: to what degree Some birders were quick to suggest that is European birdlife determined by the cir- perhaps something ominous might have cumstances in sub-Saharan Africa? That is happened in the African wintering the leading question in the book Living on areas. It took several more years before the edge: Wetlands and birds in a changing the drought south of the Sahara made Sahel. headlines in the newspapers: scorched vegetation, livestock starving to death MIGRATORY BIRDS CONNECT and millions of emaciated people. That CONTINENTS hundreds of millions of European migra- The twice annual journey of migratory 3 tory birds were dying in Africa as well is birds between breeding and wintering not surprising in hindsight, but at the grounds is quite a feat. The exhausted time this was a hotly debated issue. Wheatears we saw on the beach in Mauri- tania are a case in point: they had just cros- 1968 was the start of The Great Drought, sed the Atlantic Ocean in a single leap a period of 25 years with consistently from East Canada or Greenland to West below-average rainfall in the Sahel and ad- Africa, a distance of 5000 km. Garganey jacent vegetation zones. It was a humanita- and Ruff, breeding in the outer east of Si- rian tragedy, on top of an ecological disas- beria, cover an even longer distance of ter. The Sahara advanced to the south and 15,000 km to reach their African wintering experts were convinced that the desertifi- areas. They do it in several steps, but it cation was irreversible. Forty years later, remains as impressive. this viewpoint appears to have been too Europe accommodates more than 500 pessimistic. Satellite images show that breeding bird species, by estimate some since 1992 the Sahel has become greener 2000 millions of pairs. This equals 8000 again in the wake of an increase in rainfall, millions of post-breeding birds, of which a bouncing back from drought-related de- quarter winter south of the Sahara. For the vastation. Nonetheless, the current situa- southern European birds the fraction of tion is still unfavourable compared with trans-Saharan migrants is smaller than for that of half a century ago. What has been the birds in northern Europe where it the impact on bird populations? amounts up to 40%. Africa is of vital impor- Since the start of standardised monito- tance for the long-distance migrants bree- ring from the late 1960s onwards, popula- ding between East Canada and East Asia, tion trends of many bird populations in ranging in habitat from the Arctic tundra Europe have become available, spanning to the Mediterranean scrubland. 20 years or more. Matching trends of long- EUROPE’S LONG-DISTANCE MIGRANTS but equally so in waterbirds (large decline ARE IN DECLINE in Glossy Ibis, Ruff, Black-tailed Godwit). A Migratory bird species are in trouble, big large decline stands for a decrease of more trouble. The population estimates of Euro- than 30% in the period concerned. Conver- pean birds in 1970, 1990 and 2000, as sely, bird species wintering in the African compiled by BirdLife International, clearly forests (like European Honey-buzzard, Eu- show the point: most species wintering ropean Golden Oriole and Pied, Spotted south of the Sahara are in decline. Of the and Collared Flycatcher) seem to have been 127 species crossing the Sahara, 16 show less affected; although in decline, the an increase (13%), 36 are stable (28%), but downward slope is less steep than in the 75 (59%) are in decline. This compares species wintering in the Sahel. Many unfavourably with short-distance migrants factors play their role, but it seems beyond (33% in decline) and residents (28% in dispute that the Sahel is a key factor decline). indeed. Before embarking on a verification These downward trends were particu- of the causes behind the declines of long- larly evident in birds wintering in the distance migrants, we first have to distin- savanna (large decline in Egyptian Vulture, guish where in Africa they spend the Pallid Harrier, Steppe Eagle, Stone-Curlew) winter. After all, not all of Africa was as and wooded savanna (large decline in Black badly hit by drought as the Sahel. Kite, European Roller, Common Redstart), Nearly all Garganey from Europe and Asia spend the winter in the Sahel, where they concentrate in the 4 floodplains near Lake Chad, in the Inner Niger Delta and the Senegal Delta. The dry savannas south of the Sahara are dotted with several large wetlands, such as the Inner Niger Delta. When rainfall is abundant, the area of the Inner Niger Delta flooded during the northern winter may be as large as Belgium or The Netherlands. WHERE DO OUR MIGRANTS SPEND THE where the local Egyptian Plovers and Pain- WINTER IN AFRICA? ted Snipes are pin-pricks amidst the flocks 5 Very few European migrants winter in the of Ruff and Little Stint. Similarly, the Sahara or in the tropical rainforests. For northern Sahel forests contain few African the Sahara this is what one would expect birds, but all the more European birds (like given the lack of food and cover. Forests, Iberian Chiffchaff, Olivaceous, Bonelli’s however, are teeming with birds, over- and Subalpine Warblers). whelmingly of local origin. Perhaps this is During the northern winter, African the main reason why northern migrants bird species remain in, or move to, habitats are so rare here. The Collared Flycatcher is with a relatively stable flood supply, one of the few Paleartic species which is whereas the European migrants flood the not deterred by competition and which areas largely vacated by African species. coexists with the many African flycatcher The latter areas vary considerably in their species. food supply, both within and between Most trans-Saharan migrants do not years. Rainfall in the savannas falls in the migrate beyond the transient zone be- few months prior to the arrival of Eurasian tween the desert and the Equatorial rain- migrant. The amount of rainfall varies forest. This zone of arid and wooded considerably from one year to the next, the savannas holds several very large wetlands. very reason why migrants wintering in the During the northern winter, birdlife in Sahel face highly variable feeding condi- these marshes, as well as in the savanna, is tions. Variations in rainfall have far-rea- dominated by migrants from Eurasia. ching consequences for ‘our’ birds in Among the waterbirds, the numbers of Africa, as will be shown. local species (Whistling and Comb Duck) pale into insignificance beside the huge numbers of migrants (Garganey, Pintail, Shoveler). The same is true for the waders From Sahara to rainforest only takes a (long) day’s journey from north to south, during which the traveller witnesses a gradual change of landscape from dry, ochre and bare into wet, green and lush.