The Eurasian otter is one of the most endangered mammals in Italy and its distribution is now restricted in two isolated portions in southern Italy. However, in recent times, this species has shown a tendency to expand its range, especially northwards. It is therefore important to identify suitable areas on the border of its expansion range where the species can establish and disperse, so that these areas can be targeted for conservation actions. To this aim, the distribution, quality and connectivity of habitats of seven river catchments located in the northern portion of the current otter range in Italy were assessed. Catchments included both rivers where the otter currently occurs and where it is likely to expand in the short-medium term. An expert-based Habitat Suitability (HS) model was developed and validated using otter presence-absence data based on standard field surveys. Fine scale riverbank land cover, extra-riparian coarse scale land cover, altitude, bank slope, and human disturbance were considered as the main factors in the HS model. These variables were available or newly created in the form of digital maps (layers) and the HS model was built by sequentially filtering these layers. Connectivity was assessed within and between river basins through landscape algorithms by taking into account variables that could influence otter dispersal.Tthe results indicated that the seven rivers considered are heterogeneous both in terms of habitat suitability and in terms of connectivity. Among these, one river in particular (the river Volturno), where otters are currently present, showed one of the largest extensions of suitable habitats and the best connectivity both within the river and between the river and the neighbouring catchments, suggesting that this river could play a strategic role in the survival and expansion of otters in the surrounding areas.
Food composition of otter, Lutra lutra, was studied by the analysis of 349 spraints found during one year period (2003–2004) at the River Kamenice (Czech Republic), where Atlantic salmon, Salmo salar, fry have been stocked regularly since 1998 in a reintroduction programme for the species. Brown trout, Salmo trutta m. fario, dominated otter diet and formed 29% of all prey items and 62% of biomass of all fish eaten. The second most abundant prey (27%) was common sculpin, Cottus gobio, followed by Atlantic salmon, and grayling, Thymallus thymallus. The proportion of salmon in the diet of otters amounted to 14.5% in numerical abundance of all prey items taken and 2% in biomass of fish component of the diet. The majority (71.5%) of fish eaten by otters had a total length between 61 to 200 mm.