Common Buzzards Buteo buteo Wintering in Eastern Romania: Habitat Use and Climatic Factors Affecting their Abundance

Abstract. The Common Buzzard is a partial migrant in Eastern Europe, but its wintering densities are poorly known for this area due to a low number of studies. However, its migration patterns and wintering grounds can be affected by climate change with local fluctuations in numbers linked to weather conditions. Between 2010 and 2015 we annually carried out 15 transects/winter month in order to count the wintering population of Common Buzzards across Eastern Romania to look for climatic factors explaining variation in wintering density. Transects were controlled during two weeks from the end of the month, each covering a distance of 40 km, outlining the broadest winter monitoring of raptors in Central and Eastern Europe. Road survey was used, with a car driving at a low speed, and two observers counting birds, recording distance and habitat where birds occurred. In analyses, in addition to local weather data also 9 indices integrating weather conditions across longer time windows and larger areas were incl...