The first Eurasian beaver colony was discovered in Lower Prut Nature Reserve, located in the Republic of Moldova, approximately two centuries after the extinction of the beaver in the area. The accidental discovery of these new territories occupied by the Eurasian beaver demonstrates that the Eurasian beaver population in southeastern Romania has been expanding rapidly from 2003 and continuously towards the East by occupying favorable habitats in the meadows of the main watercourses and their tributaries. The possible dispersal routes followed by the Eurasian beaver to reach this area are exposed and presented in this paper, as well as potential future areas which may be colonized by the Eurasian beaver in Romania and the Republic of Moldova. The habitat conditions and the interaction with other wildlife species, which benefit from the natural colonization of beavers in the study area, were described and compared with other biogeographic conditions. This paper is a key step in describing and listing Castor fiber, a protected species, in the Republic of Moldova.