Due to the rapid disappearance of the Iberian desman, a project has been carried out for the reintroduction of the species, evaluating and improving the conditions to improve its habitat.

Biosfera Consultoría Ambiental was a beneficiary in the 2017 Call for Grants for the implementation of the project “Bases for the creation of satellite populations of Iberian Desman (Galemys pyrenaicus) in the Central System as a strategy for its conservation and adaptation to climate change: development of a reintroduction program”. The purpose has been to contribute to the conservation of the Iberian desman in the Central System and to improve its capacity to respond to climate change through the consolidation of known populations and the acquisition of knowledge to develop a Reintroduction Program.

The situation of the desman in the Central System is critical. In recent years, the Salamanca populations of the Cuerpo de Hombre River and the Francia River have become extinct. Two sub-basins of the Tormes River (Becedillas and Aravalle) and the headwaters of the Adaja River are still occupied, all of them in the province of Ávila, where curiously the population of Aravalle was believed to be extinct and the other two were not known to be the other two. This regression, which is more than 95%, has led to a serious situation of fragmentation and the isolation of populations.

Everything seems to indicate that the regression of the Iberian desman is not the result of a single cause, since the contraction of the distribution area has been and is being in some areas much faster than the loss of habitat quality. Several factors are involved, including the construction of dams and hydroelectric exploitation, water pollution, predation by some carnivores such as the American mink or the destruction of the banks and natural riparian vegetation. In addition, in the Central System, the overexploitation of water resources, recurrent droughts and the effects derived from climate change could be determining factors.

Faced with this serious situation, it is necessary to undertake urgent actions to restore and improve riparian habitats (planting of riparian forest, control of withdrawals and discharges, reduction of erosive processes); reduction of mortality factors (control and eradication of the American mink, correction of dangerous catchments); improvement of connectivity (permeabilization of barriers, creation of refuge areas, restoration of low-lying areas and hydrological-forest restoration in headwater areas) and population management.

It is precisely this last action, that of population management, that has been tried to be developed within the framework of this project. To this end , the situation of the populations of Castilla y León has been analyzed, from the demographic point of view and the evaluation of the possible reintroduction of the species in the eastern area of the Central System. Donor populations and habitat conditions in potential release areas have been analysed in detail, and the most appropriate extraction, transfer, release and monitoring techniques have been assessed. Based on the results, it is recommended to initiate a captive breeding program that allows to strengthen populations and facilitate the dispersal of natural populations to reduce the problems of inbreeding found. Likewise, an optimal area has been identified in the head of the Lozoya for the release of specimens with the aim of recovering the distribution area and reducing the risk of extinction in the Central System.