Nocturnal Migration of Passerines in the Desert-Highland Zone of Western Central Asia: Selected Aspects

Abstract

Annually, hundreds of millions of small passerines migrate between their breeding grounds in temperate and high latitudes of the Palaearctic and winter quarters in Africa and Asia (Moreau 1972; McClure 1974). Practically everywhere between the Atlantic and the Pacific, the migrants encounter a wide belt with the environment drastically different from the conditions these species are used to in summer and in winter. For woodland passerines from the Central and Eastern Palaearctic, this unfavourable zone includes the belt of steppes, semideserts and deserts, large highlands of Central Asia and mountain deserts. The most difficult situation may arise for passerines from the Eastern Palaearctic which spend their winter in Africa to the south of the equator. In Eastern Siberian populations of Phylloscopus trochilus or Oenanthe oenanthe, the calculated migration distance may reach 10 000 km which is 1.5–2 times longer than in the European populations (Moreau 1972). Finally, both Asian and African migrants may face the necessity to cross the world’s largest highlands in Central Asia, including the Tien Shan, Pamiro-Alay and the Himalayas. The overall length of the migratory route over the ecologically inhospitable areas of western Central Asia alone may reach 3500 km. This is quite comparable with the migratory route over the Atlantic between the Americas (Williams and Williams 1990).