Acrocephalus 28 (132): 37-38, 2007
Large scale migration of Red-footed Falcon Falco vespertinus over Kaliakra (NE Bulgaria)
Intenzivna selitev rde~enogih postovk Falco vespertinus preko Kaliakre (SV Bolgarija)
Petar Iankov1, Dimiter Georgiev2 & Bojidar Ivanov3
1 Bulgarian Society for the Protection of Birds/ BirdLife Bulgaria, P.O. Box 50, BG-1111 Sofa, Bulgaria, e-mail: petar.iankov@gmail.com
2 Bulgarian Society for the Protection of Birds/ BirdLife Bulgaria, P.O. Box 492, BG-9000 Varna, Bulgaria, e-mail: dimiter.georgiev@neophron.com
3 Institute of Zoology, 1 bul. Tzar Osvoboditel, BG-1000 Sofia, Bulgaria, e-mail: bai_bobo@yahoo.com
On 28 Sep 2006 at 15.02 h (local time) from the south-eastern edge of the village Sveti Nikola (UTM PJ20), north-eastern Bulgaria, we saw what appeared to be an endless fow of Red-footed Falcons Falco vespertinus, coming from the north-northeast over the village (UTM PJ21) and heading towards Cape Kaliakra (IBA BG051; UTM PJ10). The number of falcons that had already passed the point before our arrival is unknown, but there were birds in the whole visible part of the horizon in the south-southwestern direction, which we did not count. Starting with the falcons fying overhead between 15.02 h and 15.40 h (when no more birds were arriving) we counted a total of 809 individuals. The birds were fying at about 100 m over the steppe in a relatively narrow front of about 200-300 m, solitarily or in groups of 2-3. There were juvenile, female and male individuals, mainly fying directly with active fight, but some groups soaring. No other species of birds of prey were observed with the Red-footed Falcons. During the time of the observation, the line of the fow moved slightly westward (there was a moderate eastern wind), but the direction of fight remained the same. During the 38 minutes of observation, the falcons were passing mostly between 50 and 100 m, with some groups lower or up to 150 m height.
The birds passed over the area, which is identifed as an Important Bird Area (IBA), being a bottleneck site for migrating birds and is currently proposed as a Special Protection Area (SPA) / Natura 2000 site under the Bulgarian Biodiversity Act. However the area is threatened by investment proposals for windfarms, the major ones being from Yomy Engenering/Geopower Ltd, Universum Energy Ltd and Mitsubishi Heavy Industries. More than 100 wind turbines of over 120 m height are planned and approved by the authorities, ignoring the ornithological data.
Smaller groups of Red-footed Falcons (most probably from the same focks) were observed from 15.49 h to 15.55 h between the villages of Sveti Nikola and Balgarevo. They were hunting or perched on wires along the road. Falcons were fying northwest over the village of Balgarevo and to the northwest of it (up to 35 individuals), indicating possible return towards the north-west along the coastline after reaching Cape Kaliakra, south of which the open sea starts. This assumption was confrmed by the fact that at 17.10 h about 370 Red-footed Falcons were fying together over the coastal hills south of Kavarna, called Chirakmana - IBA BG097 White Rocks (UTM PJ00), which is further to the west-northwest along the Black Sea coast. Some birds were fying over the sea, circling over an area about 500-700 m in diameter. Most of the birds moved to the east of the site at about 17.20 h, but about 40 fying falcons were visible till 17.40 h, before dusk. The largest numbers of Red-footed Falcons previously observed in Bulgaria were recorded at Atanasovsko Lake Migration Watch Point – 890 in one day (22 Sep 1989), with 3,003 individuals in one month (Sep 1989) and the largest numbers for one season (Aug-Oct 1989) of 3,110 individuals (Ruskov 1998).
Povzetek
Avtorji podajajo nove podatke o intenzivni jesenski selitvi rdečenogih postovk Falco vespertinus preko rta Kaliakre (UTM PJ10, SV Bolgarija). Dne 28.9.2007 so našteli 809 osebkov na selitvi, verjetno pa je bilo število še večje, ker je selitev potekala tudi še pred začetkom opazovanja. Ptice so letele na relativno ozkem koridorju 200–300 m, posamič ali pa v skupinah 2-3 osebkov. Čas opazovanja je bil 38 minut, rdečenoge postovke pa so letele v smeri jug-jugozahod.
P. Iankov & D. Georgiev: Large scale migration of Red-footed Falcon Falco vespertinus over Kaliakra (NE Bulgaria)
References
Ruskov, K. (1998): Autumn Migration of the diurnal birds of prey in the region of Atanasovsko Lake Reserve near Burgas, 1989-1993, - Diploma work, Sofa University, Department of Biology, Sofa.
Arrived / Prispelo: 6.11.2006 Accepted / Sprejeto: 21.5.2007