The most characteristic environment of the park, that of the tuffaceous gorges, is crossed by streams that are still clean enough to allow the presence of demanding species such as shrimp and river crab. The spectacled salamander also lives here, a small amphibian that spends most of the daytime hours under the rocks or in the leaf litter of the undergrowth not far from the banks. Of badgers, wild boars and porcupines, there are generally only footprints or other small signs of presence, such as tufts of hair or quills. Even more difficult to spot are other mammals such as the skunk and the dormouse, while it is not uncommon in caves and hollows to come across different species of bats. Among the invertebrates we mention just a few: swarms of mayflies that appear in the summer months, plecoptera whose larvae live in the water, dragonflies with a bright livery and the high-sounding name as damsels ( Calopterix virgo ) and emperor dragonflies ( Anax imperator ).

Among the birds frequent the small canyons of the park of Marturanum the kingfisher, the white and yellow wagtails, the moorhen. Autumn and winter are the seasons of the woodcock, while the green woodpecker and the great red woodpecker are sedentary. Also reported is the localized oriole, with yellow and black plumage. In the open areas of the pastures it is possible to spot specialized predators such as the harrier and the biancone or, again among the birds of prey, the red kite; among the passerines, there is no shortage of rarities such as the calender and various species of buntings.

For some years, the park has also been home to a pair of black storks, increasingly rare frequenters of the most intact river habitats in Europe, constantly monitored also thanks to a camera located near the breeding site.