MONITORING OF THE OTTER RECOLONISATION

ABSTRACT- The Standard Method was used for three field censuses of the otter Lutra lutra distribution in Poland. In the first national survey in 1991-1994 evidence of otters was found throughout the country, with 80 % of positive sites on 2000 sites visited. Only two areas, Silesia in the south and Central Poland, had very few signs of otters. The following censuses in Central and Eastern Poland (1996-1998 and 2003) showed the otter expanded its range and recolonised much area of Central Poland, including about 700 km of rivers in the catchment of River Bzura. The number of positive 10x10 km UTM squares increased twice as compared to first survey (1991-1994). The rate of expansion was very high in com-parison to other studies in European countries. This could be due to the functional cohesion of network of rivers and lakelands in Poland. The expansion of otters was accompanied by change in habitat selection: preference for optimal habitats (unregulated rivers with tree and other vegetation cover) decreased while suboptimal and marginal habitats (e.g. channels, regulated rivers in towns) were occupied more frequently as compared to first survey. The negative side-effect of the expansion of the species is the increase of damages on fishponds, with consequent increase of pressure by fishpond owners to permit shooting of otters and/o