Declines in aquatic populations in parts of western Europe have been attributed to habitat loss, water pollution, predation by introduced American mink Neovison vison and competition by the introduced muskrat Ondatra zibethicus. Population fragmentation is more pronounced in Mediterranean populations due to increased aridity. In Israel it was a common species in the Hula swamps until the area was drained in 1957; a very limited area of the original swamp habitat remains (Qumsiyeh 1996). In Anatolia and Iran, pressure on aquatic habitat for water resources and localized competition with Rattus norvegicus (i.e., Georgia). Local population extinctions and reductions have occurred in Turkey, Georgia and other parts of this range due to drainage of swamp habitat (Qumsiyeh 1996). It is considered an agricultural pest and extensive control measures in rice fields were carried out in Macedonia in the 1980s.