The fauna of the Maramures Mountains Nature Park is specific for the Oriental Carpathians, presenting a high biodiversity, due to the ecological factors, and exposing a series of endemic species, rare for Romania and Europe.

Invertebrates

Invertebrate fauna is, obviously, less known in details. More data can be found in the entomofaunistic research (research team from the National Museum of Natural History Grigore Antipa, researchers from Cluj University, etc)
The butterflies fauna of MMNP is a representative segment for the Lepidopters of Romania. The 2007 field researchers identified 51 of lepidopters species (25% of all lepidopters from the entire national level) and were estimated 126 butterfly species, which represents 62% of the existing species from Romania. 58 from the 126 butterfly species existing in the MMNP are included the very first four categories on the National Red List (EX - one specie, CR - 4 species, EN - 13 species, VU - 30 species). (Dorel Rusti, The National Museum of Natural History Grigore Antipa, Bucharest).
Among the Diptera fauna of MMNP, 205 species were identified, 82 are Hydrophiles (Tipulomorpha, Dolichopodidae, Empidoidea, etc.), the rest are Heliophile and other (Syrphidae, Tabanidae, Tephritidae, etc.), which indicates an equilibrium between the wet and dry ecosystems.

Fishes
On the MMNP territory have been identified 22 fish species, among which there is an endemic species for the Tisa Basin (Eudontomyzon danfordi). In the inferior course of the mountain rivers: Ruscova, Frumusaua, Bistra, the number of fish species is larger than the fish species that migrate in the main river, for laying the roes. Among those species there are: Common Nase (Chondrostoma nasus), Huchen (Hucho hucho) or Barbus peloponnesius peteny - these are monuments of nature and endemic and endangered specie for the Danubian Basin, mentioned on the red list of UICN, Stroemling (Leuciscus souffia agassizi), Danubian Longbarbel Gudgeon (Gobio uranoscopus), Burbot (Lota lota).

Amphibians
During the entire research process we identified 8 species: salamander (Salamandra salamandra), the alpine newt (Triturus alpestris), the Carpathian newt (Triturus montandoni), the bittern (Bombina variegata), the toad (Bufo bufo), the green toad (Bufo viridis), the agile frog (Rana dalmatin) and the common frog (Rana temporaria).
The amphibians in the Park depend on water habitats for reproduction, mostly temporary, created by anthropic activities, except the lakes and swamps from the barren mountain area. The preservation of these habitats (leakage ditches, tractor traces, springs, holes, etc.) is vital for the permanence of the amphibian populations, taking into consideration the fact that there are very few natural habitats. In addition to this, these do not necessitate additional or expensive investments. A real danger is the introduction of fish in the alpine lakes that presently lack piscicultural fauna. Our previous experience shows that without repeated introductions, fish populations do not last for a long time, but their impact is nevertheless considerable, leading to a reduction or even the dissapearance of many invertebrate and amphibian populations.

Reptiles
The herpetofauna inventory contains 7 reptile species, among which European Grass Snake (Natrix natrix) is an endangered specie, found on the red list of IUCN. Reptiles benefit from a relatively uniform habitat, not too friendly in the Vaser valley area, unlike the more favorable areas inventoried in June. The following species were signaled to exist: Sand Lizard (Lacerta agilis), Viviparous Lizard (Lacerta vivipara), Slow Worm (Anguis fragilis), Aesculapean Snake (Elaphe longissima), European Grass Snake (Natrix natrix), Adder (Vipera berus), and Smooth Snake (Coronella austriaca).

Avifauna
During the inventories carried out until now within the Nature Park, we observed 126 bird species, from which, Crex crex appears on IUCN Red List.
In what concerns the dominant habitats in the Park, we believe that most of the present species have been identified. Their abundance (the number of observed birds) may, nevertheless, be taken into consideration only in the high altitude habitats – from the spruce fir area upwards, where the real abundance of most of the species is reflected. The species that are specific to lower areas, respectively several spruce fir species (Three-toed Woodpecker, the Pygmy Owl and the tetraonids) have been observed in a much smaller number as compared to the number observed during their pairing and nesting period.
The black grouse (Lyrurus tetrix) – with its rotation places in the Tomnatic, Stanisoara, Pop Ivan and Copilas Mountains.
The capercaillie (Tetrao urogallus) is a common species in the area, being found in the Tomnatic massif, Zarob, Gotcar, Blidereasa, Poloninca, Repedea, Lutoasa, Bucovinca.
The hazel hen (Tetrastes bonasia)
The ornithofauna is typical for the mountain area of the beech forests, the mixed forests, resinous forests and barren mountain areas. The most common species are: the dipper (Cinclus cinclus), the common sandpiper (Tringa hypoleucos), the grey wagtail (Motacilla cinerea) and the white wagtail (Motacilla alba).
One of the treasures of the Carpathians is the Golden Eagle (Aquila crysaetos), together with other prey birds like: Common Buzzard (Buteo buteo), Goshawk (Accipiter gentilis), Sparrow Hawk (Accipiter nisus) and Common Kestrel (Falco tinnunculus). Other species that are present in the studied areas are: Chaffinch (Fringilla coelebs), Cuckoo (Cuculus canorua) and Wood Pigeon (Columba palumbus).
Important species for their conservation and suggestions for their management:
White Stork (Ciconia ciconia): needs hayfields and wet pastures, for food.
Black Stork (Ciconia nigra): needs old forests for nesting and unspoiled valleys for food. Its survival is threatened by the excessive clearings within the Park.
Golden Eagle (Aquila chrysaetos): is jeopardized by the intentional maltreatment (by the inhabitants, who find it damaging) and unintentional maltreatment (the extreme sports practitioners, like climbing, paragliding, motosports and tourists), and by poaching.
Lesser-spotted Eagle (Aquila pomarina): needs old forests for nesting and meadows or extensive agricultural land mosaics for food. The corn, sunflower and rape crops are not used for hunting.
Honey Buzzard (Pernis apivorus): needs old forests for nesting; being threatened by the clearings that take place in the Park.
Peregrine (Falco peregrinus): the most important jeopardizing factors are the removal of the eggs and chicks from the nests by the falconers and the traps used by the columbophiles for catching pigeons. Capercaillie (Tetrao urogallus), Black Grouse (Tetrao tetrix) and Hazel Hen (Bonasa bonasia): are probably very seriously affected by the excessive clearings within the Park.
Stock Dove (Columba oenas): nests in hollows, therefore it needs old trees.
Common Scops Owl (Otus scops), Hoopoe (Upupa epops) and Green Woodpeckers (Picus viridis): nest in the hollows of the old trees from orchards, pastures and hayfields or in human settlements.
Pygmy Owl (Glaucidium passerinum): nests in the hollows made by Three-toed Woodpecker and it is seriously threatened by the excessive clearings.
Boreal Owl (Aegolius funereus): nests in Black Woodpecker hollows and it is seriously threatened by the excessive clearings.
Small Eagle Owl (Strix aluco) and Big Eagle Owl (Strix uralensis): use dead trees – whole or broken - for nesting. The Big Eagle Owl can also nest in prey birds nests, therefore needing old forests with standing dead trees. They are seriously threatened by the excessive clearings in the Park.
Black Woodpecker (Dryocopus martius), Grey Woodpecker (Picus canus), White-backed Woodpecker (Dendrocopus leucotos) and Three-toed Woodpecker (Picoides tridactylus): need old dead standing trees because they build their nests in hollows. They are seriously threatened by the excessive clearings in the Park.
Collared Flycatcher (Ficedula albicollis) and Red-breasted Flycatcher (Ficedula parva): need standing dead trees for nesting because they build their nests in hollows. They are seriously threatened by the excessive clearings in the Park.

Mammals
In what concerns the mammals, we can strongly state that the level of knowledge is very satisfactory. Research studies show the existence of 41 mammal species, among which 26 are mentioned on the red list of IUCN.
The most representative species from the MMNP territory are:
Elk (Cervus elaphus): the favorable biotope for elk is represented by the very spread forests, quiet, with very few or no houses, with fertile soils, cut by the fluent waters and with a lot of good gutters. One of the conditions for the spreading of elk in our country is it's sensibility towards noise.
Roe Deer (Capreolus capreolus): is a spread specie met in the mountain and plain forests. During summer it prefers the shadowed and chilled spots, and during winter it prefers the sunny spots without winds. The Roe Deer likes to eat sprouts, acorns, beech masts, blackberries.
Wild Boar (Sus scrofa): is spread from the Tisa's coppice to the mountain from the alpine area. Generally is omnivore, always living in a pack of 5-12 (20) individuals.
Grizzly Bear (Ursus arctos): it is spread all along the Carpathian chain, in big forests, less known by the human being, very quiet with rocks. When it is young likes to eat acorns, beech masts, wild apples, huckleberries, raspberries, honey, fresh grass, oats, unripe corn and when it is older likes sheep, fish, birds and their eggs, and when needed fresh cadavers.
Gray Wolf (Canis lupus): the dentition is typical for a carnivore. When it is needed it is omnivore, it can survive with fruits and vegetables, eating for example bark from the trees, but it prefers the meat. It is both a hunter and a necrophage; the wolf is an important factor for keeping the equilibrium of the nature. It lives in packs.
Little Thug (Vulpes vulpes): it prefers almost any habitat, because it can create hidings. It is also adapted to the urban areas. It is an active animal during the night but it does not hibernate.
Lynx (Lynx lynx): it lives in the mountainous area of the Maramures, in the boreal stage to the alpine stage. It lives in the forests with a high density at a high altitude. It only hunts on the land, but it can climb up in the trees, or it can swim. It is a carnivore that eats different species from rats to elks, but its main food source is represented by deer. When it is really hungry it competes with the wolf and other necropahage animals.
Wild Cat (Felis silvestris): Its favorite biotope is represented by the spread forests and the wooden springs, the bushes from the agricultural field or the ones near the waters. As a shelter and a home it chooses very old trees, a fox's burrow or the trees with no roots linked to the ground. The wild cat is an exclusively carnivore cat, its main food is represented by mice and birds. It also attacks rabbits, dormice, rats, deer's cubs, elks' cubs, as well as birds that lay eggs on the ground (partridge, pheasant, grouse).
Otter (Lutra lutra): The favorite biotope is the area between the mountains and The Danube Delta, where it can find clear waters with fish. So, it prefers the springs and the rivers with wooden and abrupt shores. It makes a home out of the galleries built in the shores. The basic food is the fish, but it also eats frogs, water rats and it also likes eggs and water birds.
Stone Marten (Martes foina): Its favorite biotope is considered the spruce and beech trees forests, to the subalpin stage, in the holes of the rocks and the abandoned nests of harpy birds and squirrels. The food is diverse: either vegetal or animal sources. Stone Marten is carnivore specie, but it frequently eats fruits, mice, rabbits, deer's cubs, birds, frogs, fish, eggs, snails, insects, honey, and in some of the cases cadavers.
European Polecat (Mustella putorius): It prefers the downs, marshes, wed forests, haystacks, old dumped buildings, as well as the sandy wooden mountains, where they build burrows. You may also find it in the human settlements. Polecat eats mice and rats, bird eggs, insects, frogs, domestic and wild birds, rabbits, fruits, honey etc.
Eurasian Badger (Meles meles): Its favorite biotope is located near the agricultural cultivated areas from hills and plains that can camouflage its burrows. It is also met in the forests from the massifs, in flowing waters downs and in the cultivated plains. It prefers the deciduous forests that offer acorns and beech masts. It is a heavy animal so it cannot walk long distances. The food is specific to the omnivore animals, so it consumes earthworms, larvae, roots, mushrooms, cereals, fruits, vegetables, eggs, mice, rabbits' kids, and sometimes cadavers.
Least Weasel (Mustella nivalis): Its favorite biotope is represented by the drier fields, from the localities included, but also on the waters' shores. The edge of a forest or a garden can represent its home. The food is represented by mice or rabbits.