The Mediterranean monk seal has the dubious distinction of being the European mammal most in danger of extinction. Fewer than eight hundred survive worldwide, the majority around the Portuguese Atlantic island of Madeira. A large colony off the coast of the West African state of Mauritania was decimated early in 1997: an estimated two hundred seals died, possibly poisoned by algae. Small numbers survive in the Ionian and Aegean seas; the largest population here, of around thirty seals, lives around the deserted islands north of Alónissos.

Monk seals can travel up to 200km a day in search of food, but they usually return to the same places to rear their pups. They have one pup every two years, and the small population is very vulnerable to disturbance. Originally, the pups would have been reared in the open, but with increasing disturbance by man, they have retreated to isolated sea caves, with partly submerged entrances, particularly around the coast of the remote islet of Pipéri.