Endangerment and protection

Reasons of endangerment

Caves and their fauna are endangered in different ways. They are largely endangered as a result of changes in hydrological regimes. These changes occur mainly due to the construction of hydropower plants to obtain energy, which primarily affects the aquatic fauna, but also the terrestrial subterranean fauna. The construction of hydropower plants and their operation requires the provision of minimum environmentally-acceptable flow in order to preserve the underground and aboveground fauna of the region.

Different forms of cave destruction – vandalism, mechanical damage caused by stone quarry activities, road construction works, tunnel digging, power industry projects, spring water intake and concrete laying, etc. – irreversibly alter or cause disappearance of subterranean animal habitats, but also of important archaeological and paleontological sites.

Croatian caves and pits are very commonly used for waste disposals and septic tanks, which directly endangers and destroys subterranean habitats and its fauna. Organic waste has a very strong adverse effect on shallow aquifers, while septic tank fluid contains a variety of different types of microorganisms that distort the biological balance and are also very harmful to the human health. In addition to organic pollution, the waste also causes inorganic pollution in the form of hazardous chemicals, such as mercury compounds from batteries, etc. The karst areas have a rather poor self-filtering capacity and the majority of pollutants that reach the underground come out with water. Modern industrial agricultural production, with its progressive and frequently uncontrolled use of artificial fertilizers and a variety of treatments for soil quality improvement and pesticides, increasingly threatens the underground and its fauna. The process of industrialization and transport development very often results in pollution from heavy metals, but also oil derivatives as a result of road accidents. All information on the pollution of caves and pits in Croatia could be reported to http://www.cistopodzemlje.info.

Many subterranean animals are endangered by their excessive and illegal collectong, primarily beetles. Beetles are mostly collected with a large number of baited traps. The collectors are frequently foreigners who do not collect the material for scientific purposes, but for collections and illegal markets.

Today, bats are increasingly endangered by the human factor. In the past they would often get killed intentionally, whereas today they mostly suffer due to human alterations to their hunting habitats and destruction of their roosts. Traditional roosts are also destroyed when the caves, which have hundred-year old bat colonies, are used for tourist purposes. For some species, it is not even necessary to destroy their roosts, but just to disturb them while they are there, e.g. during critical times when they breed or hibernate, as they tend to leave their roosts if they feel it is not safe. This is an increasingly frequent occurrence due to the exploitation of caves for tourist purposes. Unfortunately, it is not often the case that the health of bats is taken into consideration while adapting caves for touristic purposes. For some more sensitive species, the placing of a door with horizontal iron bars at the cave entrance is enough to make them abandon the cave as their roost.

Inadequate adaptations and exploitation of caves for tourist purposes have multiple adverse effects on the fauna. It results in the endangerment of many overwintering, breeding and migrating bat colonies, which are forced to look for new, often inadequate roosts. Cave adaptations commonly show three basic mistakes: inadequate building interventions, excessive number of visitors above the acceptable capacity and inadequate lighting, which results in modifications of microclimate factors. The fauna hence retreats into less accessible parts of the cave that are sometimes inconvenient for some taxa. The development of Lampenflora, as a result of inadequate lighting, brings about the destruction of speleothems, which is an important geomorphological cave factor.



  • Baković N. (2016): Širenje lampenflore u špilji Veternici (Park prirode Medvednica) u razdoblju od 2012. do 2014. godine. Subterranea Croatica 20:26-30.
  • Bedek, J., Bilandžija, H., Hamidović, D., Cvitanović, H., Dražina, T., Jalžić, B., Jalžić, V., Kovač Konrad, P., Lukić, M., Miculinić, K., Ozimec R. & Pavlek, M. (2009): Svijet ispod svijeta: Bioraznolikost špiljske faune Ogulina i Kamanja – podzemna baština od svjetske važnosti sakrivena u Karlovačkoj županiji / World Under World: Cave Fauna Biodiversity in Ogulin and Kamanje – Globally Important Subterranean Heritage Hidden in Karlovac County. Hrvatsko biospeleološko društvo, Zagreb. pp. 79.

Protection of cave fauna and their habitats

According to the Nature Protection Act (Official Gazette, 80/13, 15/18 and 14/19), caves are of special interest for the Republic of Croatia and are protected together with all cave fauna and bat species therein. General cave protection ensures that all speleothems, subterranean fauna and paleontological finds are protected against destruction, damage and collection. Additionally, all troglobionts in Croatia are strictly protected taxa according to the Ordinance on strictly protected species (Official Gazette,. 144/13 and 73/16), and cannot be killed or disturbed at any cost and neither can their habitats be endangered or destroyed.

“Cave fauna of Croatia is an exceptionally significant and valuable segment of the Croatian, European and global cave fauna. It is represented by a vast biological diversity, with an immense number of endemic and relict taxa, which is, unfortunately,  under an increasing threat. The Red List of Cave Fauna of Croatia includes 186 taxa according to threat criteria of IUCN. Endemism of the cave fauna is highly pronounced, as more than 73% (136) of the threatened taxa are endemic to Croatia, and the majority of these are stenoendemic.” Detailed data about the Red List of Cave Fauna, species biology and causes of threat are published in the Red book of Croatian cave dwelling fauna. You can find and read the book as PDF at the link.

The Croatian Agency for the Environment and Nature, in collaboration with speleological organizations, established and published The Cadaster of caves of the Republic of Croatia. Croatian Biospeleological Society is also included in this project. The Cadaster features data on 1480 caves, their morphology, geology, geomorphology, biology, paleontology and archeology. The Cadaster will serve as a helpful tool for further speleological researche, and it also provides lots of information for conservation oriented management of caves and pits. Selected data on speleological objects are publicly available online at Bioportal – Nature protection information system http://www.bioportal.hr/gis/.

All legal documents with information about cave fauna protection can be found on the websites of the Ministry of Economy and Sustainable Development and the Croatian Agency for the Environment and Nature.


  • Bedek, J., Bilandžija, H., Hamidović, D., Cvitanović, H., Dražina, T., Jalžić, B., Jalžić, V., Kovač Konrad, P., Lukić, M., Miculinić, K., Ozimec R. & Pavlek, M. (2009): Svijet ispod svijeta: Bioraznolikost špiljske faune Ogulina i Kamanja – podzemna baština od svjetske važnosti sakrivena u Karlovačkoj županiji / World Under World: Cave Fauna Biodiversity in Ogulin and Kamanje – Globally Important Subterranean Heritage Hidden in Karlovac County. Hrvatsko biospeleološko društvo, Zagreb. pp. 79.
  • Ozimec, R., Bedek, J., Gottstein, S., Jalžić, B., Slapnik, R., Štamol, V., Bilandžija, H., Dražina, T., Kletečki, E., Komerički, A., Lukić, M. & Pavlek, M. (2009): Crvena knjiga špiljske faune Hrvatske. Ministarstvo kulture, Državni Zavod za zaštitu prirode, Zagreb. pp. 371.
  • Zakon o zaštiti prirode (NN 80/13, 15/18 i 14/19)
  • Pravilnik o strogo zaštićenim vrstama (NN 144/13 i 73/16)

The Natura 2000 ecological network in Croatia

In 2013, the Natura 2000 ecological network was officially established in Croatia by the Regulation on Ecological Network (Official Gazette, 124/2013 i 105/2015). The aim of the network is to ensure conservation of Europe’s most valuable and threatened species and habitats, listed under both the Birds Directive and the Habitats Directive. The Habitat Directive also protects many caves, pits and anchialine caves and target species of cave animals and bats.

In Croatia, there are 420 caves which host specialist animal species (troglobionts). These caves may include endemic cave species that live exclusively in certain cave systems, or they can be relevant for bats, so called “Caves not open to the public – 8310”. Besides that, there are 84 speleological objects important for the protection of habitat type “Submerged or partially submerged sea caves – 8330” (Source: Croatian Agency for the Environment and Nature). Natura 2000 target species that depend on underground habitats (i.e. caves) are: Leptodirus hochenwarti, Proteus anguinus, Congeria kusceri and some species of bats.

Each EU member state shall undertake surveillance of the conservation status of natural habitats and species, with particular regard to priority natural habitat types and target species. Monitoring of the status of species listed in the EU nature directives in Natura 2000 sites provide the data needed for efficient management and conservation of natural habitat types and target species. According to the Regulation on Ecological Network (Official Gazette, 124/2013, No. 105/2015), the results of monitoring programmes shall be reported to the EU every six years.


  • Uredba o ekološkoj mreži Republike Hrvatske (NN 124/13 i 105/2015)
  • http://narodne novine.nn.hr/clanci/sluzbeni/2013_10_124_2664.html
  • http://narodne-novine.nn.hr/clanci/sluzbeni/2015_10_105_2052.html

Natura 2000 target species

Congeria kusceri

Genus Congeria inhabits the Dinaric karst in Slovenia, Croatia and Bosnia and Herzegovina. Live specimens are recorded on only 15 localities. In Croatia there is 15 localities were live specimens (six localities) or shells were found (9 localities). Live specimens in Croatia have been found in Markov ponor, Dankov ponor and cave system Lukina jama – Trojama in Lika River watershed where Congeria jalzici was found. In Neretva River, watershed populations of C. kusceri have been found in Jasena ponor, Pukotina u tunelu polje Jezero – Peračko Blato and Jama u Predolcu.

All localities where Congeria was found, in Croatia and elsewhere, are characterized by underground water flow with temporal phase of stagnant water when water regime is low. Underground water-level fluctuation regime in these localities can be significant (up to 50 m). Water temperature where C. kusceri was found is between 7.2°C – 19.4 °C (measured in Jama u Predolcu), while water temperature where C. jalzici was found is colder, from 2.1°C – 10.5 °C.

Dinaric cave clams have a long life span and live for more than 50 years. They achive sexual matuarity after 10 years (in that time their shells are 6-17 mm in lenght). As genus Congeria reaches sexual maturity at later age and produces a low number of offspring, it can be concluded that it has low capacity for population growth. Furthermore, due to the small number of localities where live specimens of Congeria have been found, a decreasing number of viable populations and adverse antropogenic pressure to their habitats (construction of traffic roads, tunnels, pollution of groundwater due to the use of pesticides and fertilizers, contamination from municipal and industrial wastewater and illegal waste disposal and changes in groundwater regime due to hydrotehnical interventions including meliorations of karst fields, power plant constructions, uncontrolled extraction of groundwater reservoirs, intensive urbanization etc.), the Red Book of Croatian cave fauna assesses Congeria kusceri as critically endangered species (CR) according to IUCN criteria.


  • Bilandžija, H., Puljas, S. & Čuković, T. (2014): Protokol praćenja stanja vrsta Congeria kusceri Bole, 1962 i Congeria jalzici Morton & Bilandžija, 2013 u Republici Hrvatskoj. Hrvatsko biospeleološko društvo, Zagreb. pp. 48.

Leptodirus hochenwarti

Leptodirus hochenwartii inhabits western part of the Dinaric karst in Slovenia, Croatia and region of Italy near Trieste. According to literature, the species is found in 53 caves in Croatia.

L. hochenwartii prefers caves and pits where air temperature ranges from 5°C to 12°C, and humidity is high. It has usually been found deeper inside the caves, walking on channel walls, on speleothems and the soil. Species size ranges from 8-11 mm. They feed on different organic materials and can also reach cave entrance in search of food.

They are endangered by destruction of habitat caused by human activities and/or pollution (waste and wastewater). Localities which are isolated from human settlements are endangered by forestry purposes like construction of forest roads or harvesting large areas. All these activities directly change underground habitats conditions and consequently endanger cave fauna populations and/or distribution. Illegal collecting is also a big problem, especially for isolated populations. Beetles are mostly collected with a large number of baited traps in which huge number of specimens could be collected. Subspecies L. h. pretneri Müller, 1926 is listed on the Red list of Croatian cave fauna and is a vulnerable species (VU) according to IUCN.


  • Hrvatsko biospeleološko društvo (2013): Nacionalni programi za praćenje stanja očuvanosti vrsta u Hrvatskoj – Tankovratić (Leptodirus hochenwartii Schmidt, 1832).

Proteus anguinus – Olm

Proteus anguinus inhabits underground rivers and lakes in the Dinaric karst in Italy near Trieste, in Slovenia, Croatia, and Bosnia and Herzegovina. The olm is the only known stigobiotic vertebrate in Europe. In Croatia, it was found from Istria to Dubrovnik, but never in the area of Ličko polje, Velebit Mt. and Zrmanja River (probably because of hydrogeological barriers). With the new genetic techniques, populations of Proteus anguinus from Istria have been confirmed as a new species – istrian olm (Proteus anguinus ssp.n.).

Body of an olm is tight and prolonged, and its length from the top of the nose to the top of the tail is 35 cm (max 40 cm). Proteus anguinus uses legs only for slow movements when looking for food, while for the escape it uses strong sweeps of its tail. The olm keeps morphological characteristics of larval form in the adult phase. On its neck, behind the head, it has three pairs of pink to intensive red gills. In waters full of oxygen it breathes with gills and through the skin, while in hypoxic waters it can also use its lungs to breathe the air. Juvenile specimens have visible eyes, while adults eyes are covered with thin skin and are not visible. The color of its skin is pink-rose, and there are only a couple of populations with black skin in Slovenia of the subspecies P. a. parkelj.

The olm prefers clean, oxygenated underground waters with temperature range between 5°C and 15°C. It can usually be found deeper inside caves and sometimes also in shallow lakes while searching for food. During spring fluxes, they can often be found on the surface. The olm has slow growth and it reaches sexual maturity when it is 14-18 years old. It can live more than 60 years. The olm feeds on beetle larvae, Mollusca and amphipods. There is evidence that, in extreme situations, it can live between 18 and 96 months without food. The olm does not have many natural enemies in caves, except some species of fishes which occasionally enter the underground habitats.

The main threats to this species are degradation of karstic underground habitats by water pollution and changes in hydrological regimes caused by construction of hydropower plants as well as import of alien (allochthonous) species in these vulnerable ecosystems. In the Red Book of Amphibians and Reptiles of Croatia it is listed in category – endangered species (EN).