Of all mammals living on the island, a special species of squirrel stands out, the so-called Caucasian (Persian) squirrel (or “galiás”, in the Lesvian dialect, Sciurus anomalus) which originates from the Asian shores and may not be seen anywhere else in Europe. Other mammals on Lesvos is the fox (Vulpes vulpres), the stone marten (Martes foina), the least weasel (Μustela nivalis), the porcupine (Erinaceus concolor), the cape hare (Lepus capensis), the European rabbit (Oryctolagus cuniculus), while some wetlands accommodate European otters.

Many bat species have also been recorded over the years. The lesser mouse-eared bat of Lesvos is a special endemic subspecies (Myotis blythi subsp lesbiacus) and stands out along with extremely endangered species such as the greater horseshoe bat (Rhinolophus ferrumequinum), the lesser mouse horseshoe bat (Rhinolophus hipposideros), the Mediterranean horseshoe bat (Rhinolophus euryale), Mehely’s horseshoe bat (Rhinolophus mehelyi), Blasius’ bat (Rhinolophus blasii) and the greater mouse-eared bat (Myotis myotis).

The seas contain a limited population of the most endangered species of Europe, namely, the Mediterranean seal (Monachus monachus) as well as three dolphin species: the common bottlenose dolphin  (Tursiops truncatus), the common dolphin (Delphinus delphis) and the striped dolphin (Stenella caeruleoalba).