The common and serotine bat, the greater horseshoe bat, otters, rabbits, hedgehogs (only in Cíes), rats, mice, wood mouse, shrews (in Cortegada) and moles are the most common land mammals on the island. Some of them were introduced by men (rat, rabbit, hedgehog). The presence of the otter, very difficult to see, was proved and though there were some doubts about its presence, reproduction and breeding is nowadays in the four archipelagos. In the “furnas” or sea caves there are often little fresh water streams which make pools used for the otters. There they clean the salinity.
There are a lot of rabbits, easy to see. They leave tracks (as their excrements, little brown balls) on the ways and also in the dens which they dig . They suffer from myxomatosis almost every year but it´s a way to regulate this species.
Other mammals are wild cats (in Cíes and Ons) or the American mink (in Ons and Sálvora). The first one comes from the domestic cat in freedom and the second one is a result of escapes or releases of animals from the continent. Both species are harmful for birds and reptiles so they are trying to extinguish them and reduce their impact.
