Blog by Dr Steffen Oppel, Senior Conservation Scientist, RSPB Centre for Conservation Science
What happens if a goat dies in the hills of Albania, or Lebanon, or in the deserts of Ethiopia? Most likely, you won’t care one bit. But the carcass festers under the sun for a day or two, and then nature’s clean-up crew arrives: vultures. And for one species a single bird could actually clean up carcasses in all of these locations within a few weeks: Egyptian Vultures are the only long-distance migrants among Eurasian vultures.
Egyptian Vultures soar and glide from Europe to Africa and back every year ©Michele Mendi / LIPU
Egyptian Vultures are not only the marathon fliers, they are also the most threatened of any of the European vultures, and there are many regional conservation projects to save them. But to save migratory species, you first need to understand where the birds migrate to. For example, Egyptian vultures have declined dramatically on the Balkan peninsula and in Italy – but do the birds breeding in those areas migrate to the same wintering areas? Will the bird that eats dead goats in Albania in July look for food in Ethiopia in December, or rather in South Sudan, Chad or Niger?
For the past 10 years researchers and conservationists have equipped Egyptian Vultures with tracking devices to document their migration. Now, in a new collaboration published this week in the journal Frontiers in Ecology and Evolution, scientists from across Europe and the Middle East have combined their data to compare Egyptian Vulture migrations: who has the longest migration, the most convoluted route, and whether the birds that breed together in one country also winter together in Africa.
Egyptian Vulture equipped with a GPS tracking device © Pavel Stepanek
The birds breeding in Spain and France had the shortest migration. They crossed the Straight of Gibraltar and then flew south to winter in Senegal, Mauritania or Mali - a journey of roughly 3000 km generally completed within 2-3 weeks. The birds breeding on the Balkan peninsula travelled roughly 2000 km more during every migratory journey, because they first flew around the Mediterranean Sea, and then around the Red Sea - detours that took on average 1-3 weeks longer.
The migration journeys of 94 individual Egyptian Vultures tracked between 2010 and 2019.
The detour around major water bodies is a typical phenomenon for many large migratory birds. Egyptian Vultures use columns of warm, rising air to get a free lift hundreds of meters up into the air, and then gradually glide for a few kilometers until they find the next free lift. From one lift to the next, they work their way to Africa at a rate of about 200 km per day. This strategy works very well over land, but fails miserably over the sea because there are no columns of rising air. Most Egyptian Vultures that tried to to take a shortcut across the Mediterranean Sea therefore paid with their lives and drowned. Compared to the almost certain death in the sea, a 2000 km detour through the Middle East does not look so bad.
Besides the amazing journeys of up to 10,983 km, the study also found that by and large the birds breeding on one part of Europe winter in the same part of Africa. Birds from western Europe wintered in western Africa, and birds from eastern Europe in eastern Africa or the Arabian peninsula. However, within these sub-populations there was an enormous variability of where birds migrated to. Birds breeding in the Balkans, for example, travelled through 28 different countries and wintered from Niger in the east to Yemen in the west – an expanse of >4000 km of desert.
This broad distribution presents real challenges for the conservation of the species.The threats to vultures vary by country – in the Middle East they get shot, in Ethiopia they get electrocuted, in Greece they get poisoned, and in Nigeria they are sold on markets. The more countries they visit the more solutions we need to develop to reduce all these threats.
Together with BirdLife International the RSPB aims to reduce threats along the flyway – and you can add your voice to speak out against the illegal killing of migratory birds.
One of the Egyptian Vultures that migrated successfully from Greece to Africa and back was poisoned upon return to Greece © Victoria Saravia / HOS
This new study has not only revealed the variability in migration of Egyptian Vultures, and their exposure to threats in >40 countries along their migratory routes, but also highlighted new avenues for research. Are populations most threatened where migratory journeys are the longest and most convoluted? How may climate change affect the bird’s ability to perform their migrations in the future? In early October, the scientists will meet for the first European Vulture Conference to discuss future collaborations that may save the only species that travels thousands of kilometers to clean up dead goats.
Egyptian Vultures are nature’s clean-up crew © Svetoslav Spasov / BSPB
Phipps WL, López-López P, Buechley ER, Oppel S, Álvarez E, Arkumarev V, Bekmansurov R, Berger-Tal O, Bermejo A, Bounas A, Alanís IC, de la Puente J, Dobrev V, Duriez O, Efrat R, Fréchet G, García J, Galán M, García-Ripollés C, Gil A, Iglesias-Lebrija JJ, Jambas J, Karyakin IV, Kobierzycki E, Kret E, Loercher F, Monteiro A, Morant Etxebarria J, Nikolov SC, Pereira J, Peške L, Ponchon C, Realinho E, Saravia V, ¸Sekercioglu ÇH, Skartsi T, ˘ Tavares J, Teodósio J, Urios V and Vallverdú N (2019) Spatial and Temporal Variability in Migration of a Soaring Raptor Across Three Continents. Front. Ecol. Evol. 7:323. doi: 10.3389/fevo.2019.00323