A broad range of migration strategies exist in avian species, and different strategies can occur in different populations of the same species. For the breeding Osprey Pandion haliaetus populations of the Mediterranean, sporadic observations of ringed birds collected in the past suggested variations in migratory and wintering behaviour. We used GPS tracking data from 41 individuals from Corsica, the Balearic Islands and continental Italy to perform the first detailed analysis of the migratory and wintering strategies of these Osprey populations. Ospreys showed heterogeneous migratory behaviour, with 73% of the individuals migrating and the remaining 27% staying all year round at breeding sites. For migratory individuals, an extremely short duration of migration (5.2 AE 2.6 days) was recorded. Mediterranean Ospreys were able to perform long non-stop flights over the open sea, sometimes overnight. They also performed pre-and post-migratory trips to secondary sites, before or after crossing the sea during both autumn and spring migration. Ospreys spent the winter at temperate latitudes and showed high plasticity in habitat selection, using marine bays, coastal lagoons/marshland and inland freshwater sites along the coasts of different countries of the Mediterranean basin. Movements and home-range areas were restricted during the wintering season. The short duration of trips and high levels of variability in migratory routes and wintering grounds revealed high behavioural plasticity among individuals, probably promoted by the relatively low seasonal variability in ecological conditions throughout the year in the Mediterranean region, and weak competition for non-breeding sites. We stress the importance of considering the diversity in migration strategies and the particular ecology of these vulnerable populations, especially in relation to proactive management measures for the species at the scale of the Mediterranean region.

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The diet of the tawny owl and the barn oa-1's. both dwelling in the Farma Valley (Tuscany) has been studied. These two strigiformes prey upon about the same micromammal species (which make up over 95% of their diets), although in different proportions. The barn owl is more microphagous than the tawny owl. Comparison with the barn o\vl's diet in other sites in Central Italy brings to light that the tawny owl's trophic niche, generally, is quite different from the born owl's, however two niches may in some way overlap, when the barn owl is roosting near \vmded areas, thereby further substantiating the euryphagy of the barn o\d. During winter, the tawny owl's diet is characterized by the crocidurinae shortage and the abundance in typically sylvan preys (Sorex min n~r r s , Clerhrionot~iys glareolrrs); during late spring sylvan preys, may be on account of the forest lesser accessibility, decrease in number, whereby the tawny owl's trophic niche appears to converge towards the usual barn owl's niche. In summer, however, the barn owl seems to predate upon crocidurinae above all, and hence full overlapping of the niche perhaps never occurs. The marked diversity repeatedly found in the samples of small mammals preyed ,upon by both these strigiformes, and their high trophic levels are well in keeping with other naturalistic a p proaches highlighting the ecological stability of the zone studied by us, which must therefore be protected.

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