Visible autumn migration of Passeriformes in the Prealpi Trevigiane.

Autumn migration of Passeriformes at two sites in Northern Italy was studied during the years 2004, 2005 and 2006. The sites, named Forcella Mostaccin (400 m a.s.l.) and Monte Pizzoc (1500 m a.s.l.) are located in the Prealps (Province of Treviso). All the monitoring was carried out between the beginning of October and mid-November. The most commonly recorded species were the Chaffinch and the Brambling. Other interesting groups included Thrushes, Warblers, Pipits and Tits. When migration was at its peak, the counts for Chaffinch and Brambling were of more than 1000 birds/hour, during the first hours after dawn in the intervening hours, the numbers of birds passing was nearly always lower with the exception of peak migration days when they remained high. We also recorded an interannual difference in the number of birds counted, both between the two sites and within the same site. The causes are currently unknown and will require the collection of more data. However, it is worth noting the total counts at both sites produced between 20,000 and 90,000 birds, making this area as one of the most important flyways in Northern Italy.