The monitoring of black storks has shown that birds migrating from Europe to Africa are under threat chiefly from changes to the environment
January 1997, the Ethiopian highlands east of Lake Tana. The signals from the transmitter we used to tag the female stork called Zuzana back in Central Bohemia are coming from a nearby village. "There's a little brown box in your hut. Please be so kind as to bring it to us," our interpreter says to an Amharic youth who introduced himself as Liew. "Our stork used to carry it on her back." Not until several hours later do we learn that Liew had thrown a stone at Zuzana, killing her. He doesn't know why he did it.
"The migratory birds that we are trying to protect in Europe spend half their life travelling and in their winter habitats. There too they need protection, but first we need to find out where they fly to and by what route," the head of the Prague Ringing Centre Jiří Formánek describes the reasons that he became one of the initiators of the African Odyssey project. In summer 1994, whilst recording a radio programme with this then 69 year-old doyen of Czech ornithologists, I for the first time mentioned the possibility of using satellites to monitor the passage of at least one stork. At the time Jiří just smiled, but by autumn that year preparations were already in full swing. To date we have mapped, in certain cases repeatedly, the migration of ten black storks under the African Odyssey project, which is supported by the public Czech Radio service. Several expeditions have also been undertaken. During its existence African Odyssey has gained incredible popularity in the Czech Republic and at the same time brought to light a number of new findings.
"Black storks are very cautious. That's why I was surprised that Liew had managed to get close to Zuzana," recalls 44 year-old ornithologist František Pojer, a participant in all the major expeditions in search of the storks. "But I soon realised that life in Ethiopia is different from ours. The entire Ethiopian highlands are very densely inhabited; wherever you turn there are people or at least domestic animals. If the storks were to keep the same distance as they do in Europe they would have to keep flying from one place to another and would not manage to catch enough food. That is why they allow domestic animals and even people come as close as a few dozen yards. Often, like Zuzana, they pay the price."
Fortunately not all black storks migrate to Ethiopia from Central Europe. Many of those which follow what is called the eastern passage across the Bosphorus or the Dardanelles change direction in Sudan and spend the winter in central Africa. Other, "westbound" storks leave Europe via the Strait of Gibraltar and winter in western Africa. (Just one stork, a male called David, stopped in southern Spain in autumn 1998 and then spent the entire winter there.)
The route of a female called Kristýna has been mapped four consecutive times: every year she flies to an area near Khossanta in eastern Senegal. Thus we managed to prove that black storks are faithful to their winter habitats in exactly the same way as they are faithful to their nesting grounds. "Imagine that you are moving to a completely new city. You won't know where to go shopping or which places are better avoided," explains 51 year-old Lubomír Peške, an African Odyssey project worker. "This applies even more for migratory birds. The better they know the landscape, the better chances they have of survival. It's easier for them to find food and to avoid their enemies."
November 1995, parched bush in eastern Chad. Mustafa, a local farmer, sits on the roof of our off-road vehicle, directing us towards the nearest lake, where we might find a male called Viktor. "Is there enough water there?" Mustafa repeats our question in surprise. "There's lots of water there!" Three hours later we finally arrive: nothing but drying-out mud, just enough water to fill two large barrels. "Is this the water you meant?" Mustafa shrugs his shoulders. "The cows drank it."
The inhabitants of Sahel grow proso and keep cattle. In years marked by lower rainfall they have to sew more land and their herds also require a larger area of pasture. At the same time there is an incredible demand placed on water sources. The water from the lake Mustafa led us to really had been drunk up by cows, and in the following days we were able to witness how the local people drove their cattle to places many kilometres away for watering. There can only be one outcome: the destruction of vegetation, soil erosion and the transformation of the landscape into semi-desert and ultimately desert. "The only time Viktor-and other wild animals too-could linger at the watering-hole was early in the morning, before the natives would arrive with their herds," Pojer says. "That meant that he had fewer places and less time for catching fish. That's why he soon had to head off south."
In Senegal the situation is incomparably more favourable, partly because wells have been built for a substantial portion of the villagers. Even so, every year Kristýna has to leave her favourite places and moves further south before returning home.
"Birds of passage searching for new stopping-places face greater risks," Peške states. "What's more, the suitable places can then become overcrowded, so they have to compete with each other. In short, they have a lower chance of survival."
Two of Kristýna's three young that we tagged with transmitters in summer 1998 did not make it far. One was shot by a hunter in France, another was died from poisoning before even leaving Bohemia. The death-rates of inexperienced fledglings less than a year old exceed fifty percent, and the figure for adult storks is probably close to ten percent.
"At a hotel in Demietta I was surprised to find the item Seasonal Birds on the menu. We went to visit the hotel's supplier," recalls Khalil Baalbaki, a 36 year-old photographer of the African Odyseey project and member of the Egypt expedition. "He showed us hundreds of yards of nets which he used to catch migrating songbirds, and then explained to us how he hunted water birds. I only hoped that none of our storks would end up entangled in them."
The pitfalls which can be encountered by birds of passage over the thousands of kilometres of their passages would make a very long list. Many larger birds die because of the faulty construction of electric pylons, for example, when their wings short-circuit the conductors.
September 1995, the northern edge of the Sahara along the Moroccan and Algerian borders. We have been driving for dozens of kilometres down a narrow road running through arid, stony country, where low, dry scrubs are the only vegetation. At the dried-up bed of the Drâa river we turn off into the desert and twenty minutes later we reach the co-ordinates where Kristýna spent the night. We find greenery and spring water in which tiny fish dart and chase. At that moment we start to suspect that Kristýna will probably not be leaving the Drâa wadi for a while.
The autumn passage to their winter habitats takes black storks between one and three months, and they make stops of several days and even weeks during the passage. The spring return journey to their nesting places is quite a lot quicker, but during these passages too the storks need to make stops. Provided they have somewhere to stop.
"Migratory birds on the move can get into the same situation as a motorist who assumes that the nearest petrol station will be a hundred kilometres away but drives for three hundred miles without coming across one," says Peške, and his words confirm the fact that storks which fly over the Balkans would enjoy altogether more frequent and longer stops than the individuals flying over western Europe. One group would have the opportunity to regain their strength, the other would not.
The journey across Africa is very difficult for storks; this is particularly true for the flight over the Sahara, when they cover distances from two hundred up to as much as five hundred kilometres a day. This makes places like the Drâa wadi all the more important to them, as they afford them food, water and rest. František Pojer believes that there cannot be many such localities. "It's not just a matter of water and food, but also trees. When birds cannot find shelter in the tops of trees and spend the night on rocks or on the ground they are much easier prey for predators. This is evidently what happened to the female called Tereza on the bare slopes of the Anti-Atlas mountains-after a while the local Berbers returned her transmitter to us."
"African Odyssey confirms that major changes in the natural environment are crucial to the fate of birds of passage. Setting up reservations in the most exposed areas and various educational programmes would help to a certain extent. But the basic issue is that desertification, deforestation or overpopulation are overstepping the boundaries of countries and continents. The threat to migratory birds is just one example of that," says Jiří Formánek.
We believe that African Odyssey is helping people, at least in the Czech Republic, to understand the scope and depth of global problems and is becoming the basis for building bridges of understanding between people who live in geographically and culturally distant countries. "For that reason, even if for no other, we will continue to monitor black storks," František Pojer concludes.
About the author
Miroslav Bobek, 32 year-old zoologist and journalist, lives in Prague, the capital city of the Czech Republic. He has worked as a programme editor at Czech Radio 2 and now he is editor-in-chief. Since 1994 he has been the manager of the African Odyssey project.