The autumn migration consists mainly of Honey-buzzard (Pernis apivorus, ca. 400,000 each autumn) and Steppe Buzzard (Buteo buteo vulpinus, 250,000+), both with daily totals peaking at 60,000 - 80,000 ind. Other numerous species include Black Kite (50,000+) Eurasian (Accipiter nisus, 4,000+) and Levant Sparrowhawk (A. brevipes, ca. 4,000), Marsh (Circus aeruginosus, 4,000+), Montagu´s (C. pygargus, 3,000+) and Pallid Harrier (C. macrourus, 1,000+ ), Booted Eagle (Aquila pennata, ca. 4,000), ...
Although counts had been conducted before at the East Black Sea bottleneck (history of research), the amazing total of 806,679 raptors counted in 2008 came as a complete surprise. At no other place in the West-Palearctic had similar numbers of migrating raptors ever been observed during autumn. The count in 2009 confirmed the importance of the bottleneck when 851,491 migrants were registered.
Currently 35 species of raptors have been recorded by the BRC. A summary of the 2008 and 2009 counts is given in Table 1.
Figure: Migration route at the Batumi bottleneck
For several complete long-distance migratory raptors BRC covers a highly significant portion of the migrants expected from presumed source areas in northeastern Europe, the western Caucasus and western Russia: Eurasian Honey-buzzard, Black Kite, Lesser Spotted Eagle and Booted Eagle. Especially remarkable are the counts for Black Kite and Marsh, Montagu’s and Pallid Harrier.
Table 1. Total numbers observed at BRC 2008 and 2009.
They are the highest total counts for these species ever registered during a single migration season. Observed migrants also included a number of internationally threatened migrants (Table 2).
Table 2. Species observed at the BRC with unfavorable international conservation status (Birdlife 2010).