The geological richness of Psiloritis, its rugged geomorphology, and the diversity of its rocks are responsible for the presence of an astonishing variety of animals that survive within the microclimatic conditions of each area.

Hundreds of bird species find here nesting grounds, hunting territories, resting places during migration, or sites for breeding. One of the few remaining populations of the Cretan wildcat (Felissilvestriscretensis), a ghost-like animal for researchers, still survives in this region.

In the depths of Psiloritis, for thousands of years, countless tiny invertebrates have thrived — blind and silent beetles, snails, centipedes, millipedes, and isopods.

The isolation of Crete has made the massif one of the most important hotspots of biodiversity and endemism in Greece, leading to its inclusion in the NATURA 2000 network.

Psiloritis is home to the Bearded Vulture or Lammergeier (Gypaetus barbatus), one of the largest and most spectacular birds of prey in Europe. The Cretan population is perhaps the last viable one in the Balkans, since poisoning and reckless development drove the species to extinction in mainland Greece. Crete now seems to be its final refuge.

The Griffon Vultures (Gyps fulvus) of Psiloritis also impress hikers with their majestic group flights, forming large colonies and nesting on precipitous cliffs and ledges, always soaring against the winds that help them rise and search for carcasses, as they feed exclusively on dead animals. Most nesting sites on Mount Ida are located toward Amari and Pano Riza, while the smoother northern slopes of Mylopotamos are used for foraging. Many other raptors complete the ornithological panorama of Psiloritis: Golden Eagles (Aquila chrysaetos), Peregrine Falcons (Falco peregrinus), Bonelli’s Eagles (Aquila fasciata), Common Buzzards (Buteo buteo), and Kestrels (Falco tinnunculus).

In the Psiloritis area we also find all three species of Cretan amphibians: the Green Toad (Bufotesviridis), the Cretan Tree Frog (Hylaarboreacretensis), and the Cretan Frog (Pelophylaxcretensis). All reptile species of Crete are present as well: Geckos (Hemidactylus turcicus, Mediodactyluskotschyi), Lizards (Podarciscretensis, Ophisops elegans), and the four snake species of the island: Leopard Snake (Zamenis situla), Montpellier Snake (Malpoloninsignitus), European Cat Snake (Telescopusfallax), and Dahl’s Whip Snake (Platycepsnajadum). Most of Crete’s mammal species are also represented here. A unique and sad absence from Psiloritis is the Cretan wild goat (Capra aegagruscretica), which was exterminated from the mountain in the 20th century with the spread of firearms. Many caves and sinkholes in the area host colonies of protected bats (Chiroptera), among them: the Erfi Cave in lowland Mylopotamos (several hundred individuals), the Kamilaris Cave near Tylissos (with at least four species in very large numbers), the Chonos Cave at Sarchos in Krousonas (home to dozens of individuals from five different species), the Kamares Cave, and many others.

Among invertebrates, snails, isopods, and several families of ground beetles exhibit narrow-endemic forms found only on the Psiloritis massif. Seventeen snail species in Mylopotamos are Cretan endemics.

Recent biodiversity hotspot studies based on the invertebrate fauna of southern Greece rank the Psiloritis massif as the second most important such hotspot in southern Greece.