The Pyrenean desman is restricted to the Pyrenees mountains (Andorra, France and Spain), as well as parts of northern and central Spain and northern Portugal. In France it occurs along the Aude, Agly, Salat, Aspe, Ossau, AriÃ¨ge, Ardour, Tet and Tech rivers. In Portugal it occurs along the Minho, Ancora, Lima, Neiva, Cavado, Ave, Leca, Douro, Vouga, Mondego, and Tejo rivers (Queiroz et al. 1998) In Spain it is found in the upper reaches of rivers in the Pyrenees, the Cantabrian mountains, the Sistema Central, the Picos de Europa and along the Deva River. It also occurs in the Sierra de Guarra north of Huesca and Infiesta, Oviedo, and Burguete, Navarro (J. Herrero pers. comm. 2006). It is found at altitudes between sea level and 2,500 m (Palomo and Gisbert 2002). In Spain, the river systems that the species occurs in flow to three different seas: Mediterranean, Atlantic and Cantabrian; hence the populations are all separated from each other.