BEX, the explicative dictionary of bats contains words, terms that are commonly used in this domain and on  the portal. In some cases, words presented in BEX do not correspond to their meaning in classic dictionaries like DEX, but are valid for the domain of bats. BEX describes these words and terms primarily from the point of view of bat research and conservation, and these can have a more restricted or broader meaning than in DEX.

If you know a word or term that is currently missing from BEX, but it is essential for the domain of bats, bat research or conservation, or especially from a letter that has no word added, please contact us.

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Bats (bat)

Bats are mammals of the order Chiroptera, which have extremely elongated fingers. Between these fingers, forearms, arms, body and legs there is a stretched skin membrane that allows active flight. Except for the poles, bats have a worldwide distribution, with more than 1,300 species currently known, mostly in tropical areas. Most bats use ultrasound for orientation and feeding, and are insectivorous. But we also know about fish-, nectar-, fruit-, blood-eating and carnivorous bats. You can find a more detailed description here.

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  • Bat Conservation International (BCI): Founded in 1982 by Dr. Merlin Tuttle, BCI is an international NGO based in the United States that is dedicated to durable protection of the 1300+ bat species of the world and the habitats used by bats, and to create a world where bats and humans coexist. BCI works at the global level, with public and private, local, regional, national or multinational partners, in order to quickly and efficiently react in case of bat conservation crisis. Website:
  • Bat Conservation Trust (BCT): Founded in 1991, BCT is the largest NGO in the UK dedicated exclusively to the conservation of bats and their habitats. The goals of BCT are to provide scientific proof to support the conservation of bats, to ensure and enhance the adaptive capacity of bat populations in a dynamic world, to win public support necessary to protect bat populations and to achieve financial stability and sustainable work conditions for BCI staff. Website:
  • Bat protection: Activity that aims to ensure the maintenance of a favorable conservation status of bat species, populations or colonies in different areas and / or roosts. Bat protection is achieved by monitoring bats, and by deciding on interventions based on monitoring results (increase, decrease or stability in the number of bats, location of colonies, etc.).
  • Bats, bat: Bats are mammals of the order Chiroptera, which have extremely elongated fingers. Between these fingers, forearms, arms, body and legs there is a stretched skin membrane that allows active flight. Except for the poles, bats have a worldwide distribution, with more than 1,300 species currently known, mostly in tropical areas. Most bats use ultrasound for orientation and feeding, and are insectivorous. But we also know about fish-, nectar-, fruit-, blood-eating and carnivorous bats. You can find a more detailed description here.


  • Carnivore: Life form that feeds on meat. In case of bats there are species that feed on small fish or birds. Such a species is the greater noctule, the largest bat species in Romania, which can capture small sized birds.
  • Cave: Any natural cavity, as defined in art. 43, paragraph 3-4 of Law 49/2011, as “a natural cavity formed in the earth’s crust, sufficiently broad and deep to allow the entrance of a human. By extension, the cave can be a system that has more than one entrance and consists of several galleries, halls, shafts and chimneys. The term also applies to cavities, which are partially or completely flooded or have been opened by blasting or human activity. The cave is a unique ecosystem whose values are of economic (water, limestone, guano, tourism, therapy), scientific (geology, minerals, underground formations, paleontological, archaeological and historical sites, sediments, cave fauna and wildlife) as well as of cultural-educational (spiritual, religious, aesthetic, recreational and educational) nature”.
  • Chiropterology: The study of bats by scientific and ethical methods, having clear and feasible goals and objectives, with results that often have direct application in durable protection of bats.
  • Colony: Aggregation of bats, in which specimens are located at a distance of max. 2 meters from each other. The notion of “colony” depends largely on the species. For example, in lesser horseshoe bats already an aggregation of 5-10 bats can be considered a colony, while several smaller aggregations, of 10-30 bats form a colony of the greater mouse-eared bat.
  • (Hibernation) colony: Aggregation of bats, which is formed during the hibernation period (1 November – 31 March) in hibernation roosts.
  • (Maternity, nursery) colony: Aggregation of bats, usually females and newborn bats, forming a colony during the maternity season (15 May – 15 August).
  • (Summer) colony: Aggregation of bats that are formed during the summer period (15 May – 15 August), but which cannot be considered a maternity colony.
  • (Transit) colony: Aggregation of bats, which is formed during the migration periods, in Spring or Autumn.


  • Directive 92/43/EEC (Habitats Directive): The directive, adopted in 1992 by the European Council, ensures the conservation of many species of rare plants and animals, as well as threatened or endemic species. The directive aims to promote the maintenance of biodiversity, while taking account of economic, social, cultural and regional aspects. The directive is the cornerstone of nature conservation policy in Europe, and together with the Birds Directive creates, across the member states of the European Union, the Natura 2000 network of protected areas, which are intended for protection against potentially damaging processes or developments.
  • Disturbance (of bats): Any gesture or human activity that may influence the environment used by bats or bat colonies, through sound, touch, heat and/or light, etc.


  • Ecosystem services: The benefits that people derive from nature in the form of goods and services provided by natural and semi-natural ecosystems. Examples: freshwater, wood, fuels, natural medicinal and pharmaceutical products, regulation of air quality, climate regulation, water regulation, erosion regulation, water purification, disease regulation, pest regulation, pollination. More examples and details here and here. Ecosystem services provided by bats are primarily the regulation of pests, and pollination.
  • EUROBATS: The international agreement on the conservation of bat populations in Europe, entering into force in 1994, and having been signed so far by a total of 36 member states. The agreement was established under the Convention on the Conservation of Migratory Species of Wild Animals, which recognizes that endangered migratory species can be protected properly only if protection activities are carried out on all the area of migration. The EUROBATS agreement aims to protect all 53 European species of bats through legislation, education, conservation measures and international cooperation with members of the agreement, but also with those who have not yet ratified the agreement. Romania signed the agreement in 2000. Website:
  • European Bat Night: International publicity and awareness event about bats, held since 1997 in over 30 European countries. In Romania the first edition was in 2000, following editions were organized by the RBPA or independently. The event usually involves photo exhibitions, general presentations about bats, and in exceptional cases site visits. About the events from other countries you find information here.


  • Feeding habitat: Area or location, which is used by bats to forage, to hunt for food. These areas could be, depending on the bat species: karst areas, mature forests, wetlands, water surfaces, meadows or pastures, gardens, but even urban areas with significant presence of insects.
  • Frugivore: Life form that feeds on fruits. Frugivore bat species are mainly distributed in the tropics, where these species are responsible for spreading seeds of the fruit that they consumed to new areas, thus helping to populate or repopulate areas.


  • Guano: Bat droppings resulting from the digestion of the food consumed. In the case of Romanian bats, the highest proportion of guano is the remains of insect exoskeletons. Guano accumulates under bat colonies, and can be used to identify the trophic spectrum of the species, by analyzing structural elements of the insect exoskeletons. At the same time, the guano can be used as natural fertilizer in the garden (although it should be heavily diluted), because it contains essential nutrients having nitrogen, potassium and phosphorus parts. See also the word “guano” in DEX.


  • Harp trap: Equipment used to capture bats, having minimal impact on the specimens studied due to its design. A Harp trap is composed of a vertical nylon network, arranged in 3-4 layers and placed above a fabric bag that collects captured specimens. Examples can be seen here. These traps can be used very efficiently at caves with small entrances (ex. 2 x 2 m), on trails in the woods, or over narrow brooks.
  • Hibernation, hibernation period: A period of lethargy in which physiological functions are minimized to allow the survival of the period without food sources. For Romanian bats the hibernation period stretches from 1 November to 31 March (with local variations due to weather conditions). More about hibernation here.
  • Hollow tree: Natural roost, which forms in time in the trunk of trees, and which is used by bats or other animals (small mammals, birds) as temporary or permanent roost. Romanian bat species that use hollow trees as roosts are the Barbastelle, Bechstein’s bat, and the noctule.


  • Insectivore: Life forms that feed on insects. Most of the 1,300 bat species are insectivores, like all species of Romanian bats. By eating big quantities of insects, bats keep under control the size of these harmful populations, this control having a beneficial effect on agriculture and forestry.
  • IUCN Red List: Created in 1963, the IUCN Red List is the most comprehensive inventory of the conservation status of species of animals and plants, and the best indicator of global biodiversity. IUCN categories are: EX – extinct, EW – extinct in the wild, CR – critically endangered, EN – endangered, VU – vulnerable, NT – near threatened, LC – least concern, DD – data deficient, NE – not evaluated by IUCN. Currently, out of the 32 Romanian bat species three are categorized as vulnerable (VU): Mehely’s horseshoe bat, the long-fingered bat, and the greater noctule. The situation of the remaining species can be studied here.


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  • Law nr. 13/1993: The law ratifying the Bern Convention on the Conservation of European Wildlife and Natural Habitats in Europe (link).
  • Law nr. 13/1998: The law ratifying the Bonn Convention on the Conservation of Migratory Species of Wild Animals (link).
  • Law nr. 205/2014: The Animal Protection Law, republished.
  • Law nr. 49/2011: Law approving Governmental Emergency Ordinance no. 57/2007 on the status of protected natural areas, the conservation of natural habitats, wild flora and fauna (link).
  • Law nr. 90/2000: The law ratifying the Convention on the Conservation of Bats in Europe, the EUROBATS Agreement (link).


  • Mammal: Class of higher vertebrates that have the body covered with fur, give live birth to their young and feed them with their milk. Bats are an order (Chiroptera) in the class of mammals (Mammalia).
  • Maternity period: The period of the formation of nursery (maternity) colonies (females and newborn pups) in order to give birth to the next generation of bats. The maternity period for Romanian bats is between 15 May and 15 August. Depending on the species and weather conditions, bats give birth to newborns from late May or early June. Initially hanging from the fur and mammary glands of females, the newborns are taken to feeding habitats, and later, when they are able to hang by themselves, are left at the roost. Newborn bats are able to fly on their own after 6-8 weeks.
  • Mating period: A period of intense activity for bats, during which bats gather at mating / swarming sites (usually at caves), and come into contact with other individuals from separate colonies, ensuring by mating an adequate level of gene flow to sustain the genetic diversity of the population. For Romanian bats the mating season takes place between the months of August and October, but there may be local or regional differences.
  • Microclimate: Term comprising the values ​​of temperature, humidity and air currents that characterize a roost or roost section used by bats. The stabile microclimate of caves and other roosts is essential for the presence of bats. Maintaining these values at their original level ​​is necessary for the protection of bats or bat colonies present in the roost.
  • Migration: Seasonal movements that usually occur in Spring and Autumn, through which animals adapt to changing temperature conditions, lack of food, or the necessity of mating. In the case of bats, the seasonal migration is the movement between Summer and Winter roosts. More details here.
  • Mine (abandoned mine): Location or underground void in a natural setting, created by human activity, which can be used as temporary or permanent roost by bats.
  • Mist net: Special net used to capture bats without physically harming them.
  • Monitoring (bat monitoring): The annual assessment of bat populations or colonies in key locations (roosts, habitats), undertaken to identify the conservation status of species, the significant increase or decrease in colony size,  in order to establish strategies for durable conservation. Bat monitoring typically includes the evaluation of maternity colonies (in Summer) and hibernation colonies (in Winter) and the assessment of mating dynamics in the mating season (Autumn). About the methodology of monitoring bats we recommend the publication of EUROBATS on the subject.


  • Nectarivore: Life form that consumes with preference the nectar of plants, flowers. In the case of  bats, nectarivores are known especially from the tropics, where through their normal feeding activity these bat species perform the pollination of plants, and thus helps in their reproduction.


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  • Patagium: Skin membrane stretching between the fingers, forearms, body and legs of the bat, allowing active flight. More details here.
  • Pettersson Elektronik AB: Manufacturer of ultrasound detectors of high quality and durability. The company is the author of the most frequently used sound analysis software, BatSound. Website:
  • Piscivore: Life form that prefers to consume fish. In Romania, Daubenton’s bat and the long-fingered bat can occasionally hunt for fish, using the long legs and claws.
  • Pollination: The process through which the pollen of one plant specimen reaches another plant, resulting in the reproduction of the species. Pollination is also an ecosystem service, which is based on the activity of pollinators (birds, bees, bats and other life forms). Over 100 tropical plant species rely on bats for pollination, bats thus having a leading role in ensuring the gene flow between these plant species. More information about the importance of pollination here.


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  • Rabies: A viral infectious disease in mammals caused by the rabies virus, a neurotropic virus of the genus Lyssavirus, Rhabdoviridae family, that is found in the saliva of infected animals. Rabies is transmitted to people from animals. Transmission usually occurs through the bite or scratch by an animal or human to another. Bats are rabies carriers, but a recent study showed that only 11 of the 12,000 bats surveyed were diagnosed with rabies (meaning, rabies that manifests itself), which represents a tiny percentage of 0.0009%. More information about rabies here.
  • Ringing: Research method, with the aim to highlight migration routes or connections between different roosts used by bats. The method involves placing a (not fully closed) ring on the forearm of the bat specimen, in a way that does not endanger the bat, and allows for the identification the ring number in case of recapturing, or observing the bat. The ringing of bats should only be done respecting a specific set of rules, and only by bat researchers authorized to undertake ringing activities.
  • Romanian Bat Protection Association (RBPA): A non-profit and apolitical organization, founded in 2000, bringing together those persons in Romania who are active in the study and protection of bats. The RBPA aims to promote chiropterological research (the study and protection of bats) in Romania, as well as the protection of environment and nature in general. Website:
  • Romanian National Bat Research Conference (RNBRC): The regular meeting of Romanian bat researchers, with the objective to share and discuss new scientific results, protection issues and sustainable communication. To date, the conference had two editions: in 2006 at Homoródfürdő, Harghita county, and in 2016 at Plaiul Foii, Braşov county.
  • Roost: Location, void, crack that is used by bats or bat colonies in different seasons of the year, to form hibernation colonies (in winter), nursery colonies (in summer), transit colonies (in spring and autumn) or during mating (in autumn). Roosts offer protection from weather (ex. temperature, humidity, wind) or physical conditions (ex. predators) during the resting period. Roosts can be natural (ex. caves, cliffs, hollow trees), artificial (ex. buildings) or anthropogenic (ex. abandoned mines), and can be used temporarily or permanently, for long (ex. during the winter) or short periods (ex. for several days during migration).
  • (Anthropogenic) roost: Locations, voids, cracks in a natural setting that have been created or modified by human activity, and which offer suitable conditions in temporarily or permanently sheltering bats or bat colonies. The most frequent anthropogenic roost type is the category of abandoned mines.
  • (Artificial) roost: Locations, voids, cracks in an urban, rural or natural setting that have been created by human activity, and which offer suitable conditions in temporarily or permanently sheltering bats or bat colonies. The most frequent artificial roost types in cities of villages are buildings (cellars and attics), bridges, cracks and spaces between building elements, etc. Bat boxes places in woodland habitats are also artificial roosts, to compensate for the loss of hollow trees.
  • (Hibernation) roost, hibernacula: Natural, anthropogenic or artificial locations, voids and cracks that harbor bats or bat colonies in the hibernation period (1 November – 31 March).
  • (Maternity, nursery) roost: Natural, anthropogenic or artificial locations, voids and cracks that shelter bat colonies formed by females and newborn bats, during the period of 15 May – 15 August. Nursery roosts usually have elevated temperatures inside, reaching in case of attics often more than 30 degrees Celsius.
  • (Mating) roost, swarming sites: Usually natural locations, voids or cracks, where a great diversity of bat species gather annually in large numbers, to mate during the August – October period.
  • (Natural) roost: Locations, voids, cracks in natural surroundings that were created by natural processes alone, and which offer suitable conditions for temporarily or permanently sheltering bats or bat colonies. The most common examples of natural shelters are caves, potholes, hollow trees, and crack, crevices in cliffs.
  • (Transit) roost: Natural, anthropogenic or artificial locations, voids and cracks that provide temporary shelter (for several days) for bats or bat colonies, during the migration seasons (spring and autumn). During migration, bats use a series of transit shelters, located along the migration route.
  • (Underground) roost: Any natural cavity (ex. caves, ravines) or artificial cavity (ex. mine, abandoned mine, cellar) that offers roost for bats or bat colonies throughout the year.


  • Sanguinivore: Life form that consumes blood as a food source from other animals. Out of the more than 1,300 bat species only three species feed on blood, all three living only in Southern America. These species feed on the blood of livestock, and only in rare cases, on the blood of humans.
  • Speleological Heritage Commission (SHC): Scientific body who authorizes activities in relation with the exploration, research, protection, exploitation and conservation of caves. The SHC is working under the Ministry of Environment, and operates following the regulation approved by the Ministry. Website:


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  • Ultrasound detector: Device that allows listening to, and recording / storing of ultrasounds emitted by bats, and which allows species identification based on the analysis of these recorded ultrasounds. Typically, ultrasound detectors convert the 20-120 kHz ultrasound range (inaudible to the human ear), into the audible spectrum (below 20 kHz).
  • Ultrasound: Sounds emitted at frequencies above 20,000 Hz (20 kHz), inaudible to the human ear. Animals that can emit ultrasound, and are using ultrasound for orientation and hunting for food, are dolphins and other marine mammals, as well as bats and some amphibians. Romanian bats emit ultrasounds in the range of 20-120 kHz, but globally the highest ultrasound frequency emitted by bats is 212 kHz.


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