Characteristics of soaring birds' spring migration over inland SE Bulgaria

Open access

Characteristics of soaring birds' spring migration over inland SE Bulgaria

We investigated the scale and characteristics of spring migration of soaring birds in Bourgas district, SE Bulgaria during three 5-day periods in March (27th-31st), April (20th-24th) and May (12th-16th) 2008. Simultaneous counts were carried out from six observation points in two separate areas (Karnobat and Sredets), located 24.5 km and 37.3 km inland from the Black Sea coast, respectively. In total, 31,049 soaring birds of at least 27 species were counted, by far the most numerous being the White Stork Ciconia ciconia (23,358 ind.), followed by the Lesser Spotted Eagle Aquila pomarina (3,112 ind.). In Karnobat area, situated farther from the Black Sea coast, the total number of soaring migrants (21,231) was more than two-fold higher than in Sredets area (9,818). Overall, there was a significant difference in flock size and flight altitude within separate area (i.e. among observation points) as well as between the two observation areas and the three 5-day periods. However, there was a substantial variance in factors significantly affecting the flock size and flight altitude among most numerous individual species. In general, birds passed at much higher altitude above Karnobat area (mean flight altitude 208.3 m ± 6.4) compared to Sredets area (mean flight altitude 130.5 m ± 4.4). In both observation areas, northern direction was the most commonly observed flight direction (46.3% of all recorded flight directions). The highest numbers of soaring migrants passed in the late afternoon, between 15.00 and 18.00 hrs - 11,554 individuals (43.0% of all birds counted). The study confirmed that the front of Western Black Sea migration route, or "Via Pontica" as part of the Mediterranean/Black Sea Flyway in SE Bulgaria, is rather wide, since the magnitude of inland migration in Bourgas district can be compared with that along the Black Sea coast, at least during spring migration. Both observation areas qualify as Important Bird Areas (IBA) of European importance according to the several BirdLife International criteria. We recommend that any new wind farms built should avoid the area of Hisar Hill south of Karnobat and the NW parts of Sredets Municipality.

Bevanger, K. (1994) Bird interactions with utility structures: collision and electrocution, causes and mitigating measures. - Ibis 136: 412-425.

Cramp, S. (ed.) (1985): Handbook of the Birds of Europe, the Middle East and North Africa. The Birds of the Western Palearctic. Vol. 4. Terns to Woodpeckers. - Oxford University Press, Oxford.

Curry-Lindahl, K. (1984): [Birds over land and sea. A global overview of bird migration.] - Albert Bonniers Press, Stockholm. (in Russian)

De Lucas, M., Janss, G., Whitfield, D. & Ferrer, M. (2008): Collision fatality of raptors in wind farms does not depend on raptor abundance. - Journal of Applied Ecology 45 (6): 1695-1703.

Dimitrov, M., Michev, T., Profirov, L., Nyagolov, K. (2005): Waterbirds of Bourgas Wetlands. Results and evaluation of the monthly waterbird monitoring 1996-2002. - Bulgarian Biodiversity Foundation & Pensoft Publishers, Sofia - Moscow.

Drewitt, A. & Langston, R. (2006): Assessing the impacts of wind farms on birds. - Ibis 148: 29-42.

European Commission (2010): Wind energy developments and Natura 2000. EU Guidance on wind energy development in accordance with the EU nature legislation. - European Commission, Brussels.

Gyllin, R. (1971): Notes on the spring migration of storks and raptors in Bulgaria. - Vogelwarte 26 (2): 182-185.

Heath, M.F. & Evans, M.I. (2000): Important Bird Areas in Europe. Priority sites for conservation. Vol. 2. Southern Europe. Birdlife Conservation Series No. 8. - Birdlife International, Cambridge.

Hilgerloh, G. (2009): The desert at Zait Bay, Egypt: a bird migration bottleneck of global importance. - Bird Conservation International 19: 338-352.

Janss, G. (2000): Avian mortality from power lines: a morphologic approach of a species-specific mortality. - Biological Conservation 95: 353-359.

Konigstedt, D. & Robel, D. (1982): Über den herbstlichen Greifvogelzug an der bulgarischen Scwarzmeerkuste. - Faunistische Abhandlungen 9 (15): 153-178.

Kostadinova, I. & Gramatikov, M. (eds.) (2007): Important Bird Areas in Bulgaria and Natura 2000. Conservation Series No. 11. - Bulgarian Society for the Protection of Birds, Sofia.

Madders, M. & Whitfield, D.P. (2006): Upland raptors and the effect of wind farm impacts. - Ibis 148: 43-56.

Michev, T., Profirov, L., Vatev, I. & Simeonov, P. (1987): Radar investigations on the autumn migration of pelicans, storks and cranes over the Bulgarian Black Sea coast. pp. 155-158 In: Actual achievements of the Bulgarian zoology. - Bulgarian Academy of Science, Sofia.

Michev, T., Profirov, L., Dimitrov, M., & Nyagolov, K. (1999): The birds of Atanasovsko Lake: Status and Checklist. Bourgas Wetlands Publication Series No. 1. - Bulgarian-Swiss Biodiversity Conservation Programme, Bourgas.

Newton, I. (2008): The migration ecology of birds. - Academic Press, London.

Noguera, J., Perez, I. & Minguez, E. (2010): Impact of terrestrial wind farms on diurnal raptors: developing spatial vulnerability index and potential vulnerability maps. - Ardeola 57 (1): 41-53.

Porter, R. & Willis, I. (1968): The autumn migration of soaring birds at the Bosphorus. - Ibis 110: 520-536.

Roberts, J. (1979): Observations of the migration of raptors and other large soaring birds in Bulgaria, 1975-1978. - Ibis 121 (3): 301-312.

Roberts, J. (1981): A contribution of the avifauna of Lake Atanasovsko, Bourgas. pp. 549-565 In: Proceedings of the Regional symposium under project 8 MAB-UNESCO, 20-24 Oct 1980, Blagoevgrad. - Bulgarian Academy of Science, Sofia.

Schwartz, S.S. (ed.) (2000): Proceedings of the National Avian-Wind Power Planning Meeting IV, 16-17 May 2000, Carmel, California. - Avian Subcommittee of the National Wind Coordinating Committee & Resolve Inc., Washington D.C.

Spaar, R. (1999): Flight behaviour of migrating raptors under varying environmental conditions. pp. 1844-1862 In: Adams, N.J. & Slotow, R.H. (eds.): Proceedings of the 22nd International Ornithological Congress, 16-22 Aug 1998, Durban, - BirdLife South Africa.

Spaar, R. & Bruderer, B. (1997): Migration by flapping or soaring: flight strategies of Marsh, Montagu's and Pallid Harriers in Southern Israel. - Condor 99: 458-469.

Smallwood, K.S. & Thelander, C.G. (2008): Bird mortality at Altamont Pass wind resource area, California. - Journal of Wildlife Management 72 (1): 215-223.

Smallwood, K.S., Rugge, L. & Morisson, M.L. (2009): Influence of behavior on bird mortality in wind energy developments. - Journal of Wildlife Management 73 (7): 1082-1098.

Thelander, C.G., Smallwood, K.S. & Rugge, L. (2003): Bird risk behaviors and fatalities at Altamont Pass wind resource area. - National Renewable Energy Laboratory, Colorado.

Zalles, J.I. & Bildstein K.L. (2000): Raptor Watch: A global Directory of Raptor Migration Sites. Birdlife Conservation Series No. 8. - Birdlife International, Cambridge & Hawk Mountain Sanctuary, Kempton.


The Journal of Bird Watching and Bird Study Association of Slovenia - DOPPS Bird Life

Journal Information

CiteScore 2017: 0.21

SCImago Journal Rank (SJR) 2017: 0.112
Source Normalized Impact per Paper (SNIP) 2017: 0.268


All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 113 113 16
PDF Downloads 27 27 6