The considerable diversity within the forests of the Parco dei Monti Sicani creates a mosaic of distinct ecological niches, supporting a rich array of fauna. The park is home to virtually all native Sicilian mammals, including the wild cat and the fox, along with several species of amphibians like the toad and the tree frog, numerous reptiles (with at least thirteen of the twenty-two native species), and over two hundred insect species. However, it is the avian population, particularly the birds of prey, that stands out for its faunal significance, with about one hundred native nesting species recorded in the park. This figure approaches the total number of bird species found throughout Sicily.

Among the most noteworthy and rare avian residents are approximately three breeding pairs of golden eagles, the falco lodaiolo, and the scarce Red Kite. Nocturnal hunters include the Barn Owl, the Owl, and the Allocco. The park also serves as a haven for numerous smaller birds that inhabit diverse ecosystems such as streams, gorges, cliffs, shrublands, meadows, and forests. Notable among these are the dipper, the nightingale, the raven, the mountain swallow, the cuckoo, the great spotted woodpecker (Dendrocopos major) — the last of its kind remaining in Sicily, the black cod, the blue tit, and the Blackcap. Additionally, the park's wetlands and artificial reservoirs support a significant population of birds of prey, including the marsh harrier and fisherman.

Many of the species mentioned are recognized by the European Community in the list of Birds of Community Interest, necessitating urgent conservation efforts. Furthermore, the Sican region has been designated as an Important Bird Area (IBA) due to its critical role in the nesting of diurnal raptors, marking it as one of the most significant locations in Italy for both density and diversity of species.