The migration of soaring birds of prey explained
By Brecht Verhelst, Tue, 08/09/2015 – 06:45
Birds of prey, commonly called raptors, have been persecuted for hundreds of years in Europe and other parts of the world, usually as suspected predators of gamebirds. But these species – which include birds like buzzards, eagles, falcons and vultures – are actually an important way to check the health of our ecosystem (they are often called ‘indicator species’) and keep things in balance.
Based on their flying strategy during migration, birds of prey can be divided into two classes: those who almost constantly flap their wings and can fly over land and water (small, active flyers like falcons and sparrowhawks), and those who rely on the lift of thermal air currents to glide and save energy (these have large and broad wings, like eagles and buzzards). These thermal soarers have to fly mainly over land as water bodies provide no thermal lift during daytime. They must also often avoid high mountain ranges.
These geographical features, especially the Mediterranean Sea, have split up the region into two main migratory routes and led to a concentration of migrants in some locations, called ‘bottlenecks’. Observations here have given us great insight into the migration strategies, population sizes and demographics of many birds of prey species, especially those that are difficult to survey on their breeding grounds.
At some sites, like in Israel, annual migration counts have been organized for decades, so the data can be used to study population crashes (for example those linked to the use of the pesticide DDT) and recoveries.
Because of its many seas and mountain ranges, Europe and the Middle East are exceptionally rich in such bottlenecks – such as Falsterbo in Sweden, the Strait of Gibraltar in Spain, the Pyrenees in France and Spain, Burgas in Bulgaria, the Bosporus and Iskenderum in Turkey, and various sites in Israel and Egypt. A recently rediscovered bottleneck is in Batumi, Georgia. Storks and birds of prey from Eastern Europe, European Russia and West Siberia fly through here, leading to daily bird counts of over 100,000 and season totals of more than a million.
SABUKO, the Society for Nature Conservation has been cooperating with the Batumi Raptor Count (BRC) to study this bottleneck and raise awareness of its value. Every year, about 30 international volunteers travel to Batumi to take part in the count of migrating raptors. They are joined by an increasing number of tourists, who stay in guesthouses run by local families. The income this generates has played a major role in convincing an entire village to stop killing migratory birds.
These kinds of success stories are few. The illegal killing of birds continues to be a major problem at many migration hotspots. Some observatories at bottlenecks have often set up very effective schemes to raise awareness among the population of the value of migratory birds.
However, campaigns need to be organized to scale up conservation efforts along the whole flyway. Schoolchildren form a great target group for educational drives about the importance of migratory birds – we should make sure that the new generation develops a different attitude towards them, focusing on protecting, not killing. These initiatives can be complemented by ecotourism development, which creates economic opportunities for local communities, generates the necessary income to sustain the conservation effort and gives them an incentive to protect the birds.