干旱区生态环境知识资源中心

The raptor population wintering in lowland farmland of northwestern Italy vas monitored during the winters of 1998-99 and 1999-2000 by means of a roadside vehicle survey. To estimate the density of wintering raptors, we recorded perpendicular distances of the birds from transect lines. Seven species of rapiers were recorded, but a sufficient number of observations to estimate density was collected only for the Common Blizzard (Buteo buteo). The extensive rice fields in the eastern part of the region and some other restricted areas, rich in humid meadows arid scattered woodlots, showed high Common Buzzard densities (1.1-1.6 birds/km(2)), but the other cultivated areas, mainly cornfields, had a significantly lower density (0.2 birds/km(2)). On the basis of these data. we estimated a wintering population of Common Buzzards of the lowland farmland, covering about 6700 km(2) in the Piemonte region of northwestern Italy of 3700 (3200-4400) birds.