The fauna of Krka National Park
The fauna of Krka National Park is very rich and diverse, with many endemic, rare and threatened species. This puts the Krka River among the most valuable natural entities in both Croatia and Europe.
Have you ever heard of the endemic species that inhabit Krka National Park? There are many subterranean animals, including freshwater cave snails, cave pseudoscorpion, cave isopod, cave polychaete, olm, and cave cricket. There are ten fish species that are endemic to the Adriatic river basins: Adriatic salmon, huchen, Adriatic dace, Dalmatian rudd, Croatian dace, Dalmatian barbel gudgeon, Adriatic barbel, Illyric ide, Visovac goby and the Dalmatian minnow?
Did you know that four species on the European endangered species list can be found in Krka National Park: greater horseshoe bat, wolf, otter and wild cat?
The otter is Europe's largest member of the marten family. It has a slender, elongated body, with short legs and reaches a mass of up to 11 kilograms. It is a protected species in Croatia.
The otter (Lutra lutra) is a carnivore belonging to the marten family (Mustelidae). It is Europe's largest marten. It has a slender, elongated body with short legs. The body can be from 100 to 120 cm in length, and its flat tail can be 35 to 55 cm long. It can reach a mass of up to 11 kg. The fur on its back is dark brown, and somewhat lighter on the neck, chest and belly. It is adapted for life in the water, including the sea. It has small ears with a valve that closes off the entrance to the hearing canal, and webbed feet. The otter has a thick layer of fat under the skin, and its thick, fatty fur protects it from the cold water. It has an excellent sense of smell, and the tips of its whiskers are very sensitive to touch, helping it to find food in murky water. Its eyes are position near the top of its head, and it can see both above and below the water's surface when it swims just under the surface, even though its sense of sight and hearing are less developed. It calls out with a quiet but clear whistle, and also snorts, squeals and growls. It builds its den, with an entrance under water, near calm river banks covered with dense vegetation, or under old trees with massive submerged roots. It is active at dusk and at night. It feeds on fish, crabs, shellfish, frogs, small mammals and other aquatic animals. It can live from 12 to 20 years. All large carnivores are the natural enemies of the otter. Today, this species is primarily threatened due to the destruction of favourable habitats, water pollution, disturbances and poaching. In Croatia, it has been protected since 1972 by the Act on the Protection of Rare and Threatened Species. The otter was included in the Red Book of Threatened Animal Species in Croatia (Mammals), and is also included in endangered species list at the European level. The Ordinance on damage compensation from 1995 prescribes a fine of HRK 30,000 for killing an otter.
The underground world of karst: the olm
Did you know that the olm is the largest subterranean aquatic animal of the Dinaric karst, and the only vertebrate adapted to living underground?
The olm (Proteus anguinus) is endemic to the Dinaric karst. It is distributed from the Soča River basin to the Trebišnjica River Basin, i.e. in Slovenia, Croatia, Bosnia and Herzegovina and Italy (only near Trieste). It was discovered in Krka National Park in the Miljacka II cave in 1989, and today it is known to inhabit four cave structures within the Park. It lives in calm, cold, underground waters that are rich in oxygen, to depths of 120 m, and is a true troglobiont. Some individuals have been reported on land in wet, underground structures (likely in search of food), and during torrential periods, they can be expelled out of the karst springs. It has a fragile, long body that is white without any pigment, though it gives off a pale pink tone due to the capillaries under the skin. The head is elongated with a rounded snout, and the eyes are undeveloped and hidden under the skin. It has short, thin legs; with three toes on the fore legs and two poorly developed toes on the hind legs. It has a flat tail that is much shorter than the body, and has a thin fin. It breathes with its lungs, but like neotic animals (those that retain larval characteristics), it retains three pairs of branching, external, bright red gills and two pairs of tufts. Its internal organs are visible through its skin. It is 25 to 30 cm long, though some individuals 40 cm long have been reported. Males are smaller than females, and during the mating season can be distinguished from the females due to their long, extruding cloaca. They feed on aquatic invertebrates, especially insect larvae and small aquatic crabs. They find their prey with their well developed chemical and mechanical receptors. Due to their slow metabolism, they can go without food for several years during the dormant period. During mating, the males protect the area from other males. The male courts the female by waving his tail towards her head, to which she responds by touching his cloaca with her snout, and following him as he releases the spermatophore. When she accepts the spermatophore with her own cloaca, the female leaves the male and lays up to 70 eggs on rock about 2 or 3 days later. They eggs hatch after 182 days at a temperature of 8ºC, after 140 days at 10ºC, after 123 days at 11ºC and after 86 days at 15ºC. In colder water, the female can retain the eggs inside her body and give birth to live young. The olm sexually matures at the age of 14 years. They are long-lived, with a life span of up to 70 years, as there are no predators threatening them in the underground waters.
Balkan whip snake
Did you know that the Balkan whip snake hunts in ambush by wrapping its body into a coil and suddenly unlashing at high speed to catch its prey from a distance?
The Balkan whip snake (Hierophis gemonensis) is distributed along the entire eastern coast of the Adriatic and Ionian Seas, from northwestern Italy, through to Albania and southern Greece, and is also found on some Adriatic and Greek islands. It is found throughout Krka National Park. It inhabits dry, rocky habitats with low, shrubby vegetation and low macchia, in sparse forests, olive groves and vineyards to altitudes of 1000 m. It remains on the ground, and only rarely climbs up onto branches. It is active by day. When disturbed, it bites. The body is grey, greyish-brown or yellowish-brown with dark spots towards the head and often with narrow light and dark stripes towards the tail. The belly is milky yellow. This is a large snake, with a slender body, large oval-shaped head and blunt snout. Its eyes are very pronounced, and it has round pupils. The tail accounts for about one-quarter the length of the body and is very thin and whip-like. It primarily feeds on lizards, other snakes, and small mammals and more rarely on young birds and eggs, and large insects (grasshoppers). Young snakes primarily feed on small lizards and insects. Mating occurs in May. In late June or early July, the female lays 3 to 10 eggs, about 25 to 40 mm in size, under dry grass and leaves. Incubation lasts from 8 to 9 weeks, depending on the temperature. Sexual maturity is achieved at three years. This snake usualy grows to about 100 cm, but sometimes can grow to 150 cm. In the wild, it can live from 15 to 20 years. Hibernation occurs from mid November to early March. This species is threatened by habitat change, urbanization, intensive agriculture, and many are killed by people out of fear. In Croatia, this snake is protected under the Ordinance on the protection of certain species of reptile (Reptilia), and the Ordinance on the proclamation of protected and strictly protected wild species.
The Krka River area abounds in various types of subterranean habitats that are inhabited or are shelter for rare and threatened animal species. The list of subterranean fauna contains about 90 terrestrial and aquatic animal species.
More than half of the recorded species are endemic to Croatia and the Dinarid mountain region, while the freshwater cave snails (Dalmatella sketi and Lanzaia skradinensis), cave pseudoscorpions of the genus Chthonius and the cave isopod of the genus Calconiscellus are endemic to the Krka National Park area. Exceptional finds includes those of the endemic freshwater cave polychaete (Marifugia cavatica), a Pliocene relict, and the endemic amphibian olm (Proteus anguinus), first discovered in the Park in 1989. Nine bat species take shelter in the caves, and of these, eight species are threatened and included in the Red Book of Mammals of Croatia. One of the largest bat colonies is that of the long-fingered bat (Myotis capaccinii). Among other animal species, the largest isopod in Croatia is found here, the endemic Dalmatian cave cricket (Dolichopoda araneiformis).Dalmatella sketi i Lanzaia skradinensis), trloglobiontni lažištipavac roda Chthonius i troglofilni jednakonožni rak roda Calconiscellus endemi su Nacionalnog parka „Krka“. Izuzetni su nalazi endemskog slatkovodnog mnogočetinaša marifugije (Marifugia cavatica), pliocenskog relikta i endemskog vodozemca čovječje ribice (Proteus anguinus), prvi put otkrivene u NP 1989. godine. Sklonište u podzemlju nalazi i devet svojti šišmiša, od kojih je osam ugroženo i uvršteno u Crvenu knjigu sisavaca Hrvatske. Među njima najbrojnija je kolonija dugonogog šišmiša (Myotis capaccinii). Od ostalih svojti čest je i izuzetno zanimljiv najveći ravnokrilac u Hrvatskoj, endemični troglofilni dalmatinski špiljski konjic (Dolichopoda araneiformis).
Krka NP endemic species
Every new discovery is of immeasurable value for the biodiversity of an area.
Every newly discovered species is of the utmost importance, especially those that are stenoendemic (meaning that it lives in only one place on Earth). The troglophile cave centipede Eupolybothrus cavernicolus Komerički & Stoev, 2013 was discovered in Krka National Park, in the Miljacka II cave and the Cave behind the mill (Miljacka IV). These are currently the only known localities of this species. Centipedes are among the largest cave invertebrates. This stenoendemic centipede is yellowish-brown to chestnut brown in color, measures about 30 mm in length with its hind legs and antennae that are more than 20 mm long. Eupolybothrus cavernicolus Komerički & Stoev, 2013, koja je otkrivena u NP „Krka“. Špilja Miljacka II i Špilja iza mlina (Miljacka IV) jedini su zasad poznati lokaliteti za ovu vrstu. Strige pripadaju najvećim beskralježnjacima u špiljama. Troglofilne špiljska velekamenjarka Eupolybothrus cavernicolus je žućkastosmeđeg do kestenjastog obojenja, duga oko 30 mm, sa zadnjim nogama i ticalima dužim od 20 mm.
In Krka NP a new springtail species has also been described – Lepidocyrtus chorus Mateos & Lukic, 2019. All specimens of the new species were collected on the old stone steps around the Miljacka Hydroelectric plant.
The name refers to its specific behaviour (Latin chorus – dancer), which is associated with its dance-like movements while seeking food and feeding. Analysis has confirmed that there are two behavioural patterns. In the first pattern, specimens keep the head and mouth in one place which making circular motions with the abdomen, to rotate around the head in both directions. In the second pattern, after time spent feeding in one place, they begin to move in a certain direction, while simultaneously continuing with the abdominal rotations, and they do not change this behaviour as something else approaches.
The holotype has a body length of 1.7 mm, without the head and furcula. Live specimens are silver in colour due to the scales covering the entire body. One dark purple spot is found laterally on each side of the fourth abdominal segment, and a purple triangular mark is found on the head between the antennae.
(photo 1: Lepidocyrtus chorus, photo 2: Eupolybothrus cavernicolus)
The invertebrates of Krka National Park are relatively poorly studied. To date, only the beetles (Coleoptera), butterflies (Lepidoptera) and dragonflies (Odonata) have been studied in detail.
In the broader Krka River area, 289 species of beetles, about 200 species of butterflies and 34 species of dragonflies have been recorded.
Among the dragonflies found near fast flowing waters, the dark blue males and brown or green females of the beautiful demoiselle and banded demoiselle (Calopteryx virgo and C. splendens) command the most attention. The most common species found near the lake-like sections of the river are the yellowish-brown scarce chaser (Libellula fulva) and scarlet dragonfly (Crocothemis erythraea). In the wetland areas, we find the Thracian emerald damselfly (Chalcolestes parvidens), which is also the only recorded habitat of this species in Croatia. The emperor dragonfly (Anax imperator) can be spotted near ponds.
To date, 40 species of day butterfly have been recorded. Among them are the protected species, swallowtail butterfly (Papilo machaon) and the scarce swallowtail (Iphiclides podalirius), and the Cleopatra (Gonepteryx cleopatra), whose population at Skradinski buk is one of the largest in Croatia. Among the brush-footed butterflies (Nymphalidae), two species are particularly interesting in terms of their characteristics and distribution: the two-tailed pasha (Charaxes jasius), one of Europe's largest butterflies, and the painted lady (Vanessa cardui), which does not winter in Europe. Among the night butterflies, the Hayward yellow underwing (Noctua haywardi), has been observed at Skradinski buk for the third time.
According to the available information, a total of 403 freshwater invertebrate species inhabit the Krka River. The most numerous are the Protozoa with 117 species and the insects (Ephemeroptera, Plecoptera, Odonata, Coleoptera, Trichoptera, Diptera, Hemiptera) with 126 known species. The best studied groups of insects are the rotifers (Rotatoria), bivalves (Mollusca), oligochaetes (Oligocheta) and crustaceans (Crustacea).
Twenty species of fish inhabit the Krka River, the most common of which are the Illyrian ide (Leuciscus illyricus), Dalmatian rudd (Scardinius erythrophthalamus hesperidicus) and brook trout (Salmo trutta m. fario).
The upper course of the Krka, upstream from Roški slap waterfall is characterised by its cold, fast waters, dominated by trout. The lower course, downstream from Roški slap, is lake-like and dominated by cyprinids. There are ten fish species that are endemic to the Adriatic river basins: Adriatic salmon, huchen, Adriatic dace, Dalmatian rudd, Croatian dace, Dalmatian barbel gudgeon, Adriatic barbel, Illyric ide, Visovac goby and the Dalmatian minnow. The wealth of endemic species is owing to the geological history of the area, and makes the Krka River a natural monument of the highest category.
The lake-like parts of the upper course, reeds, marshy meadows and ponds are abundant in amphibians, while rocky terrain with scarce vegetation are habitats for reptiles. To date, 9 species of amphibians (Amphibia) and 22 species of reptiles have been recorded in the park area. All these species are protected in Croatia, while the Red Book of Amphibians and Reptiles of Croatia includes the following: an endangered species is the loggerhead sea turtle (Caretta caretta); a vulnerable species is the olm (Proteus anguinus), the largest subterranean animal and endemic to the Dinarid karst, which inhabits four caves within the park boundaries; data deficient species are the smooth newt (Lissotriton vulgaris), which is found in the ponds in the northern part of the park, the leopard snake (Zamenis situla ) and the dice snake (Natrix tessellata); near threatened species are the common tree frog (Hyla arborea), a true acrobat in the world of the amphibians, as it can hang from one leg from a tree branch, or stand horizontally against a carob lea, the Italian wall lizard (Podarcis sicula), Hermann's tortoise (Testudo hermanni) and the European pond terrapin (Emys orbicularis). The loggerhead sea turtle only occasionally enters the brackish waters near Skradin, while the terrestrial turtles and pond terrapins are found throughout the national park. The Italian wall lizard is found in all habitats, from the marshy meadows to the dry rocky fields, and is the most common lizard species in the park. The dice snake inhabits the calmer aquatic habitats, while the leopard snake inhabits the thickets and rocky areas.
The only venomous snake found in the park is the nose-horned viper (Vipera ammodytes), which is a danger to man. There are also two semi-venomous snake species: the Eastern Montpellier's snake (Malpolon monspessulanus) and the European cat snake (Telescopus fallax). Their venom is dangerous only to reptiles, birds and small mammals.Phalacrocorax pygmaeus), bukavac (Botaurus stellaris), suri orao (Aquila chrysaetos), prugasti orao (Hieraaetus fasciatus), sivi sokol (Falco peregrinus), mali sokol (Falco columbarius), siva štijoka (Porzana parva), riđa štijoka (Porzana porzana) i velika ševa (Melanocorypha calandra). Ornitološki najzanimljivija područja u NP-u su: Skradinski buk s trščacima nizvodno i uzvodno od njega, ušće Čikole s jezerom Torkom, kanjonski dio Čikole, Visovačko jezero i Roški slap. Spomenuti lokaliteti najbolje pokazuju raznolikost i bogatstvo ptica s tipičnim predstavnicima ptica gnjezdarica, selica i zimovalica pojedinih tipova staništa. Na Roškom slapu, na malom prostoru, istovremeno se mogu promatrati ptice stijena i močvarne zajednice, a na Skradinskom buku uz močvarice mogu se vidjeti ptice šuma alepskog bora i submediteranskih kamenjara.
U NP Krka do sada je zabilježeno 46 svojti. U Crvenu knjigu sisavaca Hrvatske uvršteno je 14 svojti: u kategoriji regionalno izumrle svojte meheljev potkovnjak (Rhinolophus mehely), ugrožene svojte dugonogi šišmiš (Myotis capaccinii) i dugokrili pršnjak (Miniopterus schreibersii), rizične svojte južni potkovnjak (Rhinolophus euryale), blazijev potkovnjak (Rhinolophus blasii), velikouhi šišmiš (Myotis bechsteinii), vjerojatno ugrožene svojte vidra (Lutra lutra) te potencijalno ugrožene svojte veliki potkovnjak (Rhinolophus ferrumequinum), mali potkovnjak (Rhinolophus hipposideros), riđi šišmiš (Myotis emarginatus), veliki šišmiš (Myotis myotis), vjeverica (Sciurus vulgaris), vrtni puh (Eliomys quercinus) i vuk (Canis lupus). Na popisu ugroženih svojti u europskim razmjerima nalaze se četiri: veliki potkovnjak, vuk, vidra i divlja mačka (Felis sylvestris).
To date, 211 bird species have been recorded in Krka National Park, and of these 111 species are listed as threatened in Croatia. The national park is a nesting site for 105 species, a resting or feeding site for 90 migratory bird species, and a wintering ground for 61 species, thus making the Krka area an important international area for migratory birds. There are 9 endangered species (7 nesting species and 2 wintering species) found in the park, whose local populations account for more than 1% of the total national population. These are: pygmy cormorant (Phalacrocorax pygmaeus), Eurasian bittern (Botaurus stellaris), golden eagle (Aquila chrysaetos), Bonelli's eagle (Hieraaetus fasciatus), peregrine falcon (Falco peregrinus), merlin (Falco columbarius), little crake (Porzana parva), spotted crake (Porzana porzana) and calandra lark (Melanocorypha calandra). Ornithologically interesting areas in the national park are: Skradinski buk and its reeds, and the areas both upstream and downstream, the mouth of the Čikola River with Torak Lake, the canyon sections of the Čikola River, Visovac Lake and Roški slap. These localities best show the diversity and wealth of bird fauna, with typical representatives of nesting birds, migratory birds and wintering birds in each habitat type. At Roški slap, one can observe cliff species and wetland species together in a small area, while at Skradinski buk, one can view wetland species and the birds of the Aleppo pine forests and submediterranean rocky habitats. A total of 46 species of mammals has been recorded in Krka National Park. Of these, 14 species have been included in the Red Book of Mammals of Croatia: in the category of regionally extinct is Mehely's horseshoe bat (Rhinolophus mehely); endangered species include the long-fingered bat (Myotis capaccinii) and Schreiber's bat (Miniopterus schreibersii); vulnerable species include the Mediterranean horseshoe bat (Rhinolophus euryale), Blasius' horseshoe bat (Rhinolophus blasii), Bechstein's bat (Myotis bechsteinii); near threatened species include the otter (Lutra lutra) and greater horseshoe bat (Rhinolophus ferrumequinum), lesser horseshoe bat (Rhinolophus hipposideros), Geoffrey's bat (Myotis emarginatus), greater mouse-eared bat (Myotis myotis), red squirrel (Sciurus vulgaris), garden dormouse (Eliomys quercinus) and the wolf (Canis lupus). Four species on the European endangered species list can be found in Krka National Park: greater horseshoe bat, wolf, otter and wild cat (Felis sylvestris).