variazione del flusso diffusivo e migratorio di orso bruno (Ursus arctos Linneo 1758) dal Friuli Venezia Giulia verso il Veneto e ruolo ecologico delle aree transregionali

Abstract. Modification ofdispersaL and migration movements ofthe Brownbear from the Friuli Venezia GiuLia to Veneto region and ecological role ofthe transregional areas. The Friuli Venezia Giulia region represents an important areas for the dispersion and recolonisarion of the Brown Bear (Ursus arccos) from the Dinaric forests to the Italian central Alps, where a small isolated population has survived and recenrly has been restocked. The signs of presence, cropped from the 1970 to 2003 by forestry corps and technicians, have been studied to describe the apparent trend and the numbers and size (convex polygon method, CPM, in ha) of hot spots, areas with a apparent high presence of Brownbear from 1990 to 2001 (n=260). The cluster analysis has identified 12 Hot SpOts (pseudo t2=30,0 R2=0,97, mean CPM=12.90S ha), three ofthem area localised along the border between the Veneto and Friuli Venezia Giulia: Cansiglio (CPM=692 ha), Barcis-Piancavallo (16.S00 ha), Sauris-West carnian Alps area (17.860 ha), the last one represents an important post-denning area. From the time series analysis, the period with higher number of signs of presence, along the border Veneto-Friuli, has been from 1996 to 2000, respect the apparent increment ofsigns on ItalianSlovenia border observed in 1993 and in 1996-97. The process ofrecolonisation-diffusion, 60 km in 6 years, now seems to stop and only 1 or 2 individuals, with a large home range, are established, in the transregional areas, between Friuli and Veneto. These areas need a special transregional conservation program, coupled to the transnational program with Slovenia for enhancing the creation of Brown Bear metapopularions.