Mammals of the Macaronesian islands (the Azores, Madeira, the Canary and Cape Verde islands): redefinition of the ecological equilibrium

Abstract The fossil and subfossil mammal scenario of the oceanic islands of Macaronesia – the Azores, Madeira, and the Savage Islands (Portugal), the Canary Islands (Spain) and Cape Verde – is disconcertingly scant, consisting almost exclusively of the same taxonomic groups characterised by a homogeneous composition of species. The very few endemites can be referred essentially to three species of chiroptera in addition to three murids, which became extinct on the Canaries in historical times, and one representative of the taxonomic group of the Soricomorpha, the Canarian shrew, Crocidura canariensis Hutterer, Lopez-Hurado and Vogle 1987. It is the sole non-volant mammal still dispersed on the Canary Islands, where its occurrence is reported from Fuerteventura, La Graciosa, Lanzarote, and possibly from the two islets of Lobos and Montaña Clara. Owing to its vicinity to continental Africa, the Canary archipelago is the only one in the Eastern Atlantic islands to have been characterised by a non-volant mammalian fauna, whereas such elements do not appear to have been diffused in either the Azores or Cape Verde throughout the entire recent Quaternary. The current mammalian composition of these islands is characterised by the presence of species of almost entirely continental and anthropochorous origin. Evidence shows that the extant occurrence of non-volant mammals appears to be almost exclusively a result of human introduction during the late Holocene. The timing of such processes and the biological success of certain introductions (i.e., naturalisation) raise questions about the proper use of terms such as “natural” or “artificial” when dealing with expansions of anthropochorous range.