Český kras can also boast a wide variety of fauna. Those invertebrate groups which have been studied in detail (molluscs, butterflies, certain beetle families) show by way of their species diversity just how exceptional the area is. Many thermophilous species reach the border of their range here in Český kras and some species which live here are found nowhere else in the Czech Republic. The molluscs are especially bound to the limestone bedrock. As well as the widespread grape helix snail (Helix pomatia) and the brightly-coloured banded snail Cepaea vindobonensis, more than 70 smaller and less–noticeable species live here. The rock snails Pyramidula pusilla and Chondrina avenacea have only been recorded in the Czech Republic here.
The most noticeable of the spider species found here is ladybird spider (Eresus cinnaberinus), the brightly coloured females of which can be seen in the autumn in conserved steppe localities. By contrast, the long-jawed orb-web spider Meta menardi can be found hiding in dark cavities, caves and shafts.
Insects have the greatest species diversity and can be found everywhere in Český kras. Ground beetles are often found in the forests, including Carabus nemoralis, Carabus hortensis or Carabus coriaceus. The calosoma beetle is found here in the Czech Republic, and the stag beetle (Lucanus cervus) lives in the areas of old oak forest. In the deciduous woods in the spring we may see the tau emperor (Aglia tau) flying. On grassy areas with plants of the parsley family, the caterpillar of the swallowtail butterfly (Papilio machaon) finds its food supply. The hermit butterfly (Chazara briseis) is a very rare inhabitant of the rocky steppes. Other day–flying butterflies found in Český kras include the scarce swallowtail (Iphiclides podalirius), purple emperor (Apatura iris), graylings, fritillaries, admirals, emperors, whites and others. A common inhabitant of open, non–forested localities is the cricket Oedipoda coerulescens. The dung beetle Sisyphus schaefferi rolls its balls of dung here. In April and May we can meet the cicada (Cicadetta montana). A predator on the steppes is the larva of the rare and endangered ascalaphid owl fly Libelloides macaronius, an insect from the Neuropteran order. Several species of bumble bees and bees pollinate the flowers in the region.
The vertebrate fauna is similar to that of other parts of Central Bohemia. The Kačák stream has a relatively rich variety of fish species, including eel (Anguilla anguilla) and bullhead (Cottus gobio).
Despite the relatively heavy water pollution, a range of amphibians inhabit the area, including fire salamander (Salamandra salamandra), smooth newt (Triturus vulgaris), great crested newt (Triturus cristatus) and infrequently Alpine newt (Triturus alpestris). In the Berounka valley a strong population of marsh frog (Rana ridibunda) has been recorded as well as quite numerous populations of common toad (Bufo bufo) and green toad (Bufo viridis). Recently the range of agile frog (Rana dalmatina) has increased, whilst the common frog (Rana temporaria)is in decline.
Reptiles which are quite common on the sunny slopes include smooth snake (Coronella austriaca), and along the Berounka and Kačák water courses, dice snake (Natrix tessellata) and grass snake (Natrix natrix) are quite common. The sand lizard (Lacerta agilis) and slow worm (Anguis fragilis) are also common. The green lizard (Lacerta viridis) occurs at one locality in Český kras, which represents a biogeographical link between its known range in Křivoklátsko PLA to the north and in the central Vltava valley to the south.
When compared to the Křivoklátsko region, the only large mammal which is missing in Český kras is the red deer. The fauna of water and wetland biotopes is poor here as there are few such localities but the area’s bat community is very rich as the numerous karst crevices, fissures and caves provide suitable hiding places for them. Around 14 bat species have been recorded in the area and common species include barbastelle bat (Barbastella barbastellus), daubenton’s bat (Myotis daubentoni), greater mouse–eared bat (Myotis myotis), common long–eared bat (Plecotus auritus) and serotine (Eptesicus serotinus). The population of lesser horseshoe bat (Rhinolophus hipposideros) is slowly increasing. As a rarity of Český kras, the only sighting of greater horseshoe bat (Rhinolophus ferrumequinum) in Bohemia was made here. The occurrence of Nathusius’s pipistrelle (Pipistrellus nathusii) is also a rarity and recently a summer colony of Northern bat (Eptesicus nilssoni) has been identified.
Badgers (Meles meles) and beech martens (Martes foina) are probably more common here than in the surrounding areas. The badger is able to use karst cavities to build its burrows and the rugged character of the limestone hills make a suitable habitat for both species. The wild boar (Sus scrofa) has become a permanent inhabitant of the forested areas in recent years. Among insectivores we can find western (Erinaceus europaeus) and eastern (Erinaceus concolor) hedgehogs and pygmy shrew (Sorex minutus). Common rodents in the area are common or hazel dormouse (Muscardinus avellanarius) and fat dormouse (Glis glis). A population of field vole (Microtus agrestis) has been recorded in the Karlické údolí. On the meadows near Loděnice we can find a native population of European souslik (Spermophilus citellus). In recent years, two non-indigenous species, the raccoon-dog (Nyctereutes procyonoides) and the American mink (Mustella vison), which escaped from fur farms, have found their way into Český kras. Occasionally fallow deer (Dama dama) or red deer (Cervus elaphus) wander into the area from the Hřebeny hills to the south. Mouflon (Ovis musimon) have been introduced into the eastern section of the PLA.
As the PLA area offers a wide range of nesting opportunities, the birdlife of Český kras is richer than in the surrounding areas, especially for songbirds. Among the notable forest species found in the area are black woodpecker (Dryocopus martius), red–breasted flycatcher (Ficedula parva), woodlark (Lullula arborea), honey buzzard (Pernis apivorus) and stock dove (Columba oenas). A rare nesting species is the hobby (Falco subbuteo). Among birds bound to steppe biotopes, we can mention the quail (Coturnix coturnix) and barred warbler (Sylvia nisoria), and the hoopoe (Upupa epops) infrequently nests near Šanův kout. Rarer species bound to the rocky areas include jackdaw (Corvus monedula), eagle owl (Bubo bubo), tawny owl (Strix aluco) and the occasionally nesting wheatear (Oenanthe oenanthe). The wallcreeper (Tichodroma muraria) overwinters in the area every year. Up to the present 174 bird species have been identified on the territory of Český kras PLA, of which 125 species are known to nest here and another 7 species are thought to nest here.