The mammals most easily observable are the roe deer (Capreolus capreolus) and the European hare (Lepus europaeus).
The roe deer hides by day in the woods, while at dusk and dawn it grazes meadows. The European hare is an animal related to open areas like meadows, where it is easily observable in the spring during the breeding season.
Other mammals that live in the resurgences area are nocturnal and, therefore, are difficult to see. One of the carnivores are typical of humid forests of the lower Friuli plain is the polecat (Mustela putorius), long about half meter tail included. It feeds mainly on small mammals, amphibians and fish. Its name is due to the presence of glands at the base of the tail (anal glands) that release strongly odorous substances when the animal is alarmed or when it marks the territory. It is a species in decline due to environmental changes that reduce the wooded areas and adversely affect the food supply. The polecat is included in the IUCN Red List of animals in Italy and is specially protected by law.
In the same family, the weasels, are also the stone marten (Martes foina) and the weasel (Mustela nivalis), while the otter (Lutra lutra),a species characteristic of resurgences and water courses and who lived along the Stella river until the mid-seventies, is now extinct in the region.
In the resurgences area lives also the fox (Vulpes vulpes) which, despite is a carnivore, has a diet rich in fruits and berries.
Small mammals (insectivores and rodents) are certainly the most numerous.
Among the insectivores of this environment include the western hedgehog (Erinaceus europaeus italicus), the mole (Talpa europaea) and some species of the soricidi family as the Southern water shrew (Neomys anomalus), found along the waterways. It is likely the presence of the Udine shrew (Sorex arunchi).
The rodents are present in all reseourgences areas. Along streams lives water vole (Arvicola amphibius), and in dense vegetation marshes the harvest mouse (Micromys minutus).
In the driest areas, in croplands and wooded areas live the voles (genus Microtus) and the wood mouse (Apodemus sylvaticus).
Among the woods rodents there is the striped field mouse (Apodemus agrarius) and the common dormouse (Muscardinus avellanarius), which builds a spherical nest in the dense vegetation in the undergrowth and shrubs.
Over the past twenty years the squirrel (Sciurus vulgaris) has expanded in the lowland woods, as black form as that the red one. This species is considered vulnerable by the IUCN Red List of animals in Italy because it could be replaced by other exotic species of squirrels in areas where these are present (in Italy: in Piedmont and Liguria).
In Britain, the European squirrel is on the verge of extinction due to the presence of the gray squirrel, imported from North America, which is in competition for food and space with the European Red Squirrel.