The largest mammal is the brown hare (Lepus europaeus), in danger of becoming extinct, not on account of excessive hunting, but because of the rabbits released in nature by man, which are very competitive and threaten to oust the hare from its natural habitat.
Other species that have been recorded include the eastern hedgehog (Erinaceus concolor), different species of rats and mice, the black rat and house mice (Rattus rattus and Mus domesticus), a bat species, the pipistrelle (Pipistrellus sp.) and the pygmy horseshoe bat (Suncus etruscus).
The total absence of predatory mammals is also due to human activities.
Milos is home to one of the most rare birds of prey, the Eleonora’s falcon (Falco eleonora) which lives and reproduces in the Aegean islands and on Crete. Other birds of prey that one can come across on the island of Milos are the Bonelli’s eagle (Hieraeetus fasciatus), in danger of becoming extinct on account of hunting, the buzzard (Buteo buteo) and the kestrel (Falco tinnunculus), a small falcon.
Finally, among nocturnal predatory birds we can list the little owl (Athene noctua) and the barn owl (Tyto alba).
Other birds living permanently on Milos are the chucar (Alectoris chukar), the rock dove (Columba livia), the collared dove (Streptopelia decaocto) and various small species of sparrow such as the crested lark (Galerida cristata), the skylark (Alauda arvensis), the wren (Troglodytes troglodytes), the house sparrow (Passer domesticus), the hooded crow (Corvus corone cornix) and the raven (Corvus corax).
Among sea–birds, the two most common ones are the herring gull (Larus cacchinans) and the shag (Phalacrocorax aristotelis).
Milos’ small wetlands are vital to migratory birds, as they are used by them as rest places in their long trip. Bird watching has recorded a host of both rare and more common species of birds that go through the island in spring and in autumn, while migrating.
Some of the species worth noting here are the very rare short-toed eagle (Circaetus gallicus), the golden eagle (Aquila chrysaetos), enough of the harriers (Circus) species, most of the Herons species (Ardeidae), the swans, the flamingo (Phoenicopterus ruber), many riparian species, and also woodcocks (Scolopax rusticola), doves, thrushes (Turdus), shrikes and many others.
The reptilian fauna is both rich and rare. Fresh water springs in two areas of the island, the airport and Saint John Siderianos, are natural habitats for the Rana ridibunda frogs throughout the year. There are also two kinds of lizard, the balkan green lizard (Lacerta trilineata) and the Milos wall lizard (Podarcis milensis). The latter is endemic and can be found only on Milos, Kimolos, Polyegos, and Antimilos.
Milos is rich in snakes, another form of reptilian fauna that can be found the most known being the blunt-nosed viper (Macrovipera schweizeri), also endemic to the island. Other snakes are the cat snake (Telescopus fallax), the grass snake (Natrix natrix) and the leopard snake (Elaphe situla).