A complex population structure of the Black Kite (Milvus migrans, Accipitridae) in eastern Asia: migratory and sedentary populations

The Black Kite, Milvus migrans, is a common accipitrid opportunistic predator with a giant distribution range covering vast areas in the continents of Eurasia, Australia and Africa. This species is characterized by a complex population structure which consists of settlements of two ecotypes: the southern sedentary populations and the northern populations of seasonal migrants. To winter, the birds of the northern populations annually undertake long-distance migrations to the breeding grounds of the southern populations. The problem is that both migrants and residents belong to the same Asian subspecies M. m. lineatus and actually are indistinguishable in their phenotype at the southern parts of the subspecies range. This poses apparent problems for field observations of the birds to both population types. As a result, the population structure of the species remains especially dubious as regards the territories of the Russian Far East, China and Japan. The authors have tried to gather all available information on the population status of M. m. lineatus in the east of Asia and to systematize the scattered data on the population dynamics, migrations and genetic markers of the different populations. Particular attention has been paid to the populations from China, because the published information is still extremely scarce. Based on the records of the species from public databases, we could delineate the current breeding range of the migratory and resident populations of the lineatus race in Asia. This, in turn, allows us to discuss the origin, distribution, and history of spreading of both population types of the Black Kite in Northeast and East Asia. We assume that the sedentary populations in China, South Korea and Japan share a common origin. We separately consider the kite population on the island of Taiwan, whence the subspecies M. m. formosanus was described about a century ago. There are reasons to believe that no birds of this form have survived on the island until today. In addition, possible reasons for a clear decline in black kite numbers at the end of the 20th century are discussed for the large territory of the Russian Far East.