The Bats of Bulgaria

Vladimir A. Beshkov

Summary

The twenty-nine species of bats that occur at present in Bulgaria include nearly all of the species extant in the European fauna. A number of these species are very common, others are rare, and still others have been seen and found only once or several times. The variety of bat species is well documented, and their number and distribution have been relatively well researched. However, their biology - especially their reproduction, feeding habits, and migration patterns - has been studied to a much lesser degree.

The habitat or sites of the bat colonies are well documented, for they occur almost exclusively in caves, mine shafts, other underground structures, and (upon rare occasions) cliffs. Species composition and abundance, seasonal fluctuations in bat numbers, threatening factors, and changes in the variety of species during the last three to four decades have all been well studied and documented. The ecto- and endoparasites of cave-dwelling bats are also extremely well researched.

The Bulgarian studies of bats have focused primarily on species that inhabit caves, rather than those that dwell in hollowed-out trees, human dwelling sites, etc. Very little information is available for these species.

All bat species are protected by law (Order No. 1021/1989 of the Ministry of Environment) with fines, penalties, and claim damages imposed for every destroyed specimen. This law has been publicized and popularized through a poster and information sheet distributed throughout Bulgaria in 1989.

Two species of bats - Myotis emarginatus and Myotis capaccinii - are listed in the Bulgarian Red Data Book (1985) as endangered species. One abandoned mineshaft, near the village of Golak in Sofia County, has been given protected status due to the large bat colonies that inhabit it. The legislative order granting this protected status (Order No. 1141/1981) was issued by the Ministry of Environment. Dozens of other caves with important archaeological, historic, or natural features enjoy special status as protected areas and also serve as bat habitats.

The non-cave dwelling bats are relatively less endangered than cave-dwellers, whose habitats are located in cave vaults and arches and in the deep cracks of the cave walls. The large colonies in greatest danger from anthropogenetic influences are those that dwell in readily accessible and heavily visited caves. There the bats are disturbed, chased, and sometimes destroyed by visitors lacking ecological awareness. The worst damage to bats is inflicted through the lighting or fires in caves or cave entrances (especially during winter), and through direct destruction. Great harm has also been inflicted through attempts at commercial use of caves (for example, for storage, cheese manufacturing and aging, or conversion into restaurants or tourist centers).

At present, no research has been conducted to study the impact of pesticides or industrial and chemical pollution on the population sizes and status of bats in Bulgaria.

The warm and lowland regions of Bulgaria (such as the Strouma River valley, the eastern Rhodopes, and the southern third of the Black Sea coast) have the greatest abundance and variety of bat species. Those areas, and the lowland regions around 700-800 meters a.s.l., contain the largest bat colonies, with total numbers ranging from 2000 to 3000. At higher elevations, both the species richness and abundance of bats that inhabit underground dwellings decrease.

The large bat colonies are distributed unevenly in Bulgaria. This is a consequence primarily of geological factors, such as the irregular distribution of limestone and stalactite formations with caves.

A Brief History of Bat Research in Bulgaria

The first report on the bat fauna of Bulgaria is found in the work of Kovachev at the end of the 19th century and the beginning of the 20th. He gives a brief account of the eight species he discovered for the first time in Bulgaria.

Around 1908-1909, Ivan Buresch visited the caves near the Lakatnick train station several times, gathering bats for Professor Porfery Bahmatiev's experiments pertaining to the anabiosis in bats. In 1917 Buresch published the first work specifically on bats in Bulgaria, in which he provided detailed descriptions of the morphology of 14 species.

Heinrich (1936) announced the existence of 16 species of bats, and described three new subspecies in Bulgaria (these subspecies designations were later rejected by other scientists).

Buresch (1941) published a report on the banding of 138 bats in Bulgaria, not one of which was later found. Banding was later undertaken by a group of young zoologists. By 1 July 1956, they had banded 626 bats (Beron, 1958). The number of bandings eventually increased to 3296 specimens (Beron, 1962; Beron, 1963).

Atanasov and Peschev (1963) identified 24 species of bats for Bulgaria, and described numerous new locations. The first study of the ecology of bats was conducted by Beron (1964), who identified 27 caves unique for their bats, inhabited by approximately fifty-thousand individuals.

The three catalogues on Bulgarian cave fauna (Gueorguiev and Beron, 1962; Beron and Gueorgiev, 1967; Beron 1972) enumerate every species of bats found in the Bulgarian caves and describe all of their underground habitats.

Studies pertaining to the discovery of individual species and their habitats were published by Markov and Jambazov (1962), Gaisler and Hanak (1964), Hanak and Jossifov (1959), and Kwartirnikov (1956, 1957). Beshkov and Beron (1962) published information on the distribution and biology of the rare species Barbastella barbastellus, Vespertilio sertinus, and Myotis emarginatus. Kalchev and Beshkov (1963) announced the finding of Tadarida teniotis and Molossidae south of Plovdiv. Cerveny et al. (1971) found twelve species of bats in the Rhodopes, some of which are new or very rare species for Bulgaria. Kowatschev and Simeonov (1970) published studies of a number of characters of the skeleton of Rhinolphidae and Vespertilionidae species. Gaisler (1970) studied the temperature conditions of the winter habitat of 19 bat species, but unfortunately does not distinguish between measurements taken in Czechoslovakia and Bulgaria.

Buresch and Beron (1962) found three bats, of three different species, banded in the Soviet Union and recovered in Bulgaria. Horacek et al. (1974) undertook a study of the species richness and diurnal cycle of bats in a number of Rhodope caves. Pandurska (1992) announced a second location for the very rare Tadarida teniotis in southwestern Bulgaria.

Researchers from the Institute of Zoology of the Bulgarian Academy of Sciences, together with amateur speleologists, were particularly active in studies of habitat caves, and their respective colonies, in the period 1988-1989. Their work was financed by the Ministry of Environment. This detailed report was used extensively in preparing this paper.

The parasites found on the Bulgarian bats are well researched. Helminths have been studied by Buchvarov (1963) and especially by Jantschev and Stoikova (1973). The ectoparasites have been researched by Kolebinova and Beron (1965), Dusbabek (1964), Kolebinova (1967, 1970), and Beron (1968, 1974).

Many popular articles on the biology and protection of bats have been written by V. Beshkov, P. Beron, V. Popov, and others. Scientific information and other practical knowledge has been communicated through magazines, newspapers, radio, and television. The popular science documentary "Bats" deserves particular mention. It was directed by K. Grigoriev and produced by the "Vreme" studio in 1971. The colored poster entreating bat protection, with a 6000-copy issue, and distributed throughout Bulgaria during 1989-1990, also deserves mention.

Information Gaps

The absence of data or lack of information in certain areas is due primarily to biases in the interests of the researchers of this field. The majority of them have focused on the bat fauna in the field, others on bat parasitology. As a consequence, the species composition of the bats - twenty-nine species - is well established, as are their abundance (which can be described under the headings "numerous," "common," "rare," and "extremely rare"). Their distribution is also relatively well known, particularly in terms of the habitats of the cave-dwellers and the character of their preferred summer and winter shelter. We also have partial knowledge of the temperature conditions of their dwellings during the different seasons.

The ectoparasites of bats, such as ticks, fleas, wingless flies, and helminths, are also well studied. But once again this pertains mainly to the more numerous species and the predominantly cave-dwelling species. Of the latter, greater information is available on those that spend their days on, or hibernate on, the walls and arches of the caves, as they are more readily noticed and captured. These include species from the genera Rhinolophus, Myotis, Plecotus, and Miniopterus. Species that dwell and hide in cave cracks and among stalactites (such as members of the genera Vepertilio and Myotis) have been studied to a much smaller degree.

Bat researchers have only recently begun to capture bats using mist nets placed at the entrance of caves. This method has allowed researchers to demonstrate that species thought to be rare or extremely rare are considerably more numerous. These species had not been noticed and remained unnoticed simply because of their habit of hiding and our inability to capture them.

The major gaps in scientific information about the bats in Bulgaria pertain to the following areas.

Current Status

In 1988-89, a group of researchers from the Institute of Zoology of the Bulgarian Academy of Sciences, together with amateur speleologists (primarily students and members of speleology clubs around Saofia) conducted a thematic study entitled "Proouchvane na sustoyanieto i stepenta na zastrashenost na prilepnite colonyi v Bulgaria s ogled na tyahnata zashtita" ("Study of the Status and Level of Threat of the Bat Colonies of Bulgaria With a View Toward Their Protection"). The study was commissioned by the Bulgarian Ministry of Environment. To a great extent, the data presented in this section is derived from this study. Other data was gathered during the period 1955-1988. Studies conducted from 1990-1992 provided a third source of data.

Areas Requiring Further Study

A more appropriate term might be "less familiar territories." Areas that have been least studied are:

1. The upper reaches of the mountains, especially mountains with silicate cliff composition but lacking caves. Although bats in nocturnal flight have been observed in these areas, there are virtually no records of captured specimens. At the same time, it is precisely in these regions that we may expect to find in greater abundance species that in the lower altitudes are considered "extremely rare," like Vespertilio murinus, Barbastella barbastellus, Myotis bechsteinii, Myotis nattereri, Vespertilio nilssonii, and perhaps others.

2. Relatively few bat specimens are known from the wide-ranging Danubian and Thracian plains of Bulgaria. Very little work has been conducted in these areas due to the lack of caves. Consequently, the species composition of the bat population is probably considerably different from that of the "cave" regions.

3. It is highly probable that new colonies of bats could be discovered in cave openings located on vertical cliffs and in gorges created as a result of water erosion - sites that are inaccessible without mountain climbing gear. Information about significant bat colony finds, and of diurnal or hibernating bats dwelling in caves whose entrances are located on steep vertical cliffs, is growing. Bulgaria has hundreds of such unexplored cave openings.

Species Richness

With its twenty-nine species, Bulgaria's bat fauna is richer than that of the countries of Central or Northern Europe, and measures up well against the Mediterranean countries or those closest in proximity to the Mediterranean Sea. Among the European states, Bulgaria rates "high" on the scale of species diversity. Compared to other areas of the Palearctic, Bulgaria rates as "average."

Rare Species

All of the species of bats encountered in Bulgaria are either abundant or commonly encountered - there is a difference! - in Europe, the Near East, North Africa, and even Australia (one species).

The majority of species that are deemed rare or even extremely rare in Bulgaria are in other areas common, or at least abundant. This is the case with Barbastella barbastellus, Vespertilio murinus, Myotis nattereri, and Myotis bechsteinii, which are extremely rare in Bulgaria, but common in Central and Northern Europe. The same is also true of Tadarida teniotis, Vespertilio savii, and Vespertilio kuhlii, which are rare in Bulgaria, but not so in Southern Europe or the Near East.

No species that are frequently encountered in Bulgaria are rare in other parts of their ranges. The value of the Bulgarian bat fauna lies in the existence of large colonies of most species common to our biogeographic region. Throughout the European states, such colonies no longer exist or are extinct due to human impacts. Bulgaria falls into the region where many northern species reach the southernmost borders of their distribution, and some southern species have their northernmost occurrence. Consequently, the presence of rare species is not high.

Endemism

As a consequence of their extreme mobility, bats have large distributional ranges (excluding certain island fauna). All bats in the Bulgarian fauna are encountered across wide areas. Some inhabit virtually all of Europe and portions of neighboring continents as well, including some of their far-flung corners. No bat species are endemic to Bulgaria or the Balkan peninsula. Three endemic subspecies have been described in the territory of Bulgaria: Myotis capaccinii bureschi, Miniopterus schreibersii inexpectatus, and Myotis mystacinus bulgaricus (these are the three from Heinrich`s 1936 work). Contemporary specialists, however, do not recognize these as valid subspecies.

Ecosystems, Habitats, and Unique Communities

The problems in preserving the diversity of species and the distribution of the large- and medium-sized cave-dwelling bats extant in Bulgaria will be examined under this heading.

The large bat colonies are distributed extremely unevenly throughout the territory of the country. Their locations are determined by the existence of caves that are conducive to their survival and removed from human activities. The importance of the latter quality is demonstrated by the eviction or destruction of some cave-dwelling colonies whose caves are frequented by visitors, or through the adaptation of caves to suit tourist or business needs.

During the active period of the year, between April through October, Miniopterus schreibersii is the dominant large bat. In the majority of cases, this species constitutes 70-95% of the bat population in the colonies. Myotis myotis and Myotis blythi can coexist with Miniopterus schreibersii, constituting some 5-10% of the bats present. These two species are virtually indistinguishable without capturing and measuring them, as their biological characteristics are very similar. In the following text they are referred to as the "large Myotis," for in many cases their capture has been impossible due to the inaccessible height of their location within their colonies, or to the disturbance and frightening away of the colony. Myotis daubentonii is also found on occasion.

In still rarer instances, Myotis capaccinii inhabits the same caves. Individual or tens of Rhinolophus ferrumequinum have also been found to cohabit these caves, and occasionally individual Rhinolophus hipposideros live there as well. Rhinolophus blasii and Rhinolophus euryale can also be found on rare occasion. These latter two species are quite similar in their biological characteristics. In cases where the species are not definitely distinguished, or when both species are determined to occur, they are termed "average Rhinolophus," as they are average in size when compared with the much smaller Rhinolophus hipposideros or the much larger Rhinolophus ferrumequinum. In many cases they live along with dozens and at times hundreds of Myotis emarginatus. This latter species is rarely found alone, but cohabits with the Rhinolophus bats.

During the second half of October and the first half of November, some of the larger colonies leave their summer quarters and migrate to underground sites that are appropriate for hibernation. In such instances, up to ten species can be found in a single cave. This includes bats that during the summer are never found in caves.

Miniopterus schreibersii hibernate in large groups, some 10,200 individuals having been observed in one place. The two large Myotis species hibernate in groups of up to 800; Myotis capaccinii in groups of up to 3000; Rhinolophus ferrumequinum in groups of up to 400; the two average Rhinolophus in groups of up to 250-300. The remaining species occur in groups of several dozen or as single individuals.

A list of Bulgaria's 13 most significant bat dwelling caves follows. These caves are of primary importance for the existence of bats in the country in that many serve as important reproduction centers or "nurseries" and as roosting and hibernation sites for thousands of bats. Some of these caves are protected by the nature protection acts or other legislative bills. They are marked here with an asterisk (*). But in the majority of caves, bats are extremely vulnerable, and indications of their destruction or disturbance - including long sticks, dead bats, and the lighting of fires - are in evidence.

1. "Nanin Kamak," near the village of Musselievo in Nikopolsko County.

This cave is located approximately 1 km from the village, at the base of a crown of limestone cliffs and at the uppermost reach of the characteristic hill. During five visits between the end of April 1968 and February 1989, 1500 to 3250 Miniopterus schreibersii were observed, and a few tens of Myotis blythi; on some visits, between 400-1500 Myotis capaccinii, up to 50 average Rhinolophus, and up to a few hundred Rhinolophus ferrumequinum were reported.

During two winter visits (January and February) no bats were found. They flee, as they are often disturbed during purposeless visits by local youths who at times destroy them. The cave in itself is unremarkable, except for the existence of the large bat colonies within.

2. "Serpanovata Peshtera," near the Cherpish train station in the Iskar gorge.

During several repeated warm season observations of the chasm at the end of the cave (which is 14 meters deep) and of the cave's arches, 300-400 Rhinolophus ferrumequinum, 2600-2900 Miniopterus schreibersii, approximately 60 Myotis myotis, and an individual Rhinolophus ferrumequinum were reported.

During winter visits, approximately 1500 Miniopterus schreibersii, 21 Myotis myotis, and 30 Rhinolophus ferrumequinum were found. On another winter visit, no bats were found. The difficult drop into the cave's interior as well as the height of the arches on the upper lever assure that these bats will be relatively well protected from human visitation.

* 3. "Parnitsite," near the village of Bejanovo in the Lovetch region.

This cave serves as a water route for an underground stream. It is 2950 m long, with an upper entrance where the water enters from underground, and a lower one where the water exits. Visits made during the summer season established the presence of 550-600 Miniopterus schreibersii, 700-800 Myotis myotis and Myotis blythi, and hundreds of Myotis capaccinii. During other visits, 2700-2800 Myotis myotis and Myotis blythi and approximately 800 Miniopterus schreibersii were observed.

During a winter visit there were found hibernating in the cave approximately 4000 Miniopterus schreibersii, between 2000 and 2500 Myotis capaccinii, several tens of Rhinolophus ferrumequinum, and individual representatives of other species. The cave is generally visited by speleologists, both specialists and hobbyists, who leave the bats undisturbed.

* 4. The mineshaft near the village of Golak in the Kostenets area, located in the Ihtiman Sredna Gora mountain range.

The mineshaft was dug approximately 400 years ago to extract iron ore. The shaft is 63 meters long, and 10-12 meters in height and width. In 1916, Ivan Buresch estimated that 20,000 bats inhabited the mineshaft. In March 1958, the bat population was estimated at 3000-5000. In subsequent visits between the end of March and 10 October of various years, the bat colonies were found to consist of 90-95% Miniopterus schreibersii, and to range from 3000-5000 individuals during March, April, and October to 12,000-14,000 individuals in June and July. During the winter, the hibernating colony was usually estimated to contain from 2000-3000 individuals. The minimum population reported was 1200, and the maximum 9800-9900. During the winter of 1970-71, no bats were found hibernating in the mineshaft.

Two other species of bats - large ones, but in considerably fewer numbers - have also been found in the shaft: Myotis, with up to 40-50 individuals, and Rhinolophus blasii, occurring as single individuals. Rhinolophus ferrumequinum and Rhinolophus hipposideros have also been found on occasion.

The shaft serves as the "maternity ward" or "nursery" for thousands of Miniopterus schreibersii. At the end of June and in the first days of July they flock in from other places. Their protection is ensured by special order No:1141/1981 of the Ministry of Environment. However, urgent measures are needed for their actual protection.

5. "Gargina Dupka" near the village of Mostove in the Assenovgrad region in the Rhodope Mountains.

Huge amounts of bat guano are found in this cave. It is approximately 300 m2 in size, and ranges from 16-18 meters in height. It has served as a gathering site for millennia.

During a total of seven visits, both winter and summer, colonies of several thousand Miniopterus schreibersii have been observed. In February 1989, 10,000 individuals of this species were found. Local inhabitants have made a practice of setting fire to rubber and plastic garbage at the cavesite. A great many bat corpses have been found. This colony is unique and remarkable for its persistence and permanence. Its population is extremely vulnerable.

6. The cliff crevices near the "Madarskyiat Konnik" (the Madara Knight) near Shoumen.

The crevice is located 100 to 120 meters from the bas-relief of the knight, at an upper-left angle of 50 to 55 degrees. The climb to the crevice is dangerous, as is the drop to the ledge, which is unstable.

During the summer 2600-2650 Miniopterus schreibersii and 2900-3000 large Myotis have been observed. These craggy cliffs serve as the colony's "nursery."

In the middle of October, the bat population disappears. The high wind currents and low temperatures of the openings are not conducive to hibernation.

The quantities of guano indicate that this site is inhabited by large colonies. Special protection is needed.

* 7. The cave near the village of Prolas, near the town of Turgovishte.

Summer season visit results: in 1958, several thousand Miniopterus schreibersii and hundreds of Myotis; in 1970, the same, plus a few tens of Rhinolophus ferrumequinum; in 1988, 13,500-14,000 Miniopterus schreibersii and approximately 350 large Myotis; in 1989, 8000-9000 Miniopterus schreibersii and individuals of other species.

Winter season visit results: in 1971, 5000-8000 Miniopterus schreibersii, 300-400 large Myotis, and approximately 300 Rhinolophus ferrumequinum; in 1988, 5000-7000 Miniopterus schreibersii, approximately 150 large Myotis, and some 20 Rhinolophus ferrumequinum.

This cave is visited frequently by local youths from the village of Prolas, who light fires and destroy the bats. This colony is extremely important, and quick and effective preservation measures are urgently needed.

* 8. "Orlovata Peshtera" in the Zelenich area, near the town of Kotel.

This cave is about 100 meters long with a simple configuration. During visits in the summer of 1958, around 5000 Miniopterus schreibersii and several tens of Rhinolophus ferrumequinum and large Myotis were reported. In 1989, approximately 3700 Miniopterus schreibersii were found, including newborn bats.

No bats were reported during winter visits in 1989. The protection of this cave is absolutely necessary. Speleologists from the town of Kotel have observed large colonies on numerous occasions. The cave is readily accessible and frequently visited by people, including groups that disturb the bats.

9. "Yars-Iny" or "Prilepnata Doupka," near the Sredna Arda train station in the Kurdjaly area.

The cave is approximately 15 meters long, 8-9 meters wide, and 4 meters high.

Summer observations: in June 1989, 7000-8000 large Myotis were counted, most of which were in advanced stages of pregnancy. A small number of newborns were included.

Winter observations: no signs of bats were found in a November 1989 visit.

In April 1989, a group of youths from Kurdjaly set a huge bonfire in the cave and with sticks and branches killed several hundred bats, primarily Myotis and somewhat fewer Miniopterus schreibersii. Urgent protection of this cave is needed in order to prevent further incidents of this kind.

* 10. "Ponora," a water cave near the village of Chiren in the Vratsa region.

This cave contains underwater lakes and streams, and is approximately 3.5 km long. The cave still shows signs of abandoned attempts to convert it into a tourist center, and is in a sorry state. A water pump at the entrance emits unbearable noise. During the years 1958- 1966, large colonies of Miniopterus schreibersii, large Myotis, and Myotis capaccinii were observed, along with hundreds of Rhinolophus ferrumequinum and Rhinolophus blasii, with other species found as single individuals. Amateur speleologists have observed colonies of 3000 to 6500 members.

During the summer of 1988, 900 large Myotis were observed. On another visit the same year, the water pump was emitting intense noise, so that only individual bats remained. A colony of nearly 100 individuals was found within 50 meters of the cave, inside a cliff crevice with a "chimney" above the crevice. Several weeks later, 300-400 Rhinolophus blasii were observed resting in the cliff's crevices near the cave.

* 11. "Orlova Chooka," near the village of Pepelina in the Rousse region.

This is an extremely large, spacious, branching cave. It is partially electrified and an object of high tourism activity. At the time of its discovery, nearly 50 years ago, huge bat colonies were observed, both during the summer and winter.

During numerous visits over the last 30 years and throughout the four seasons, large colonies of Miniopterus schreibersii, large Myotis, Rhinolophus ferrumequinum, and others have been observed. Over the past decade, the numbers have progressively declined due to the human presence. In April 1988 hundreds of bats were seen to fly though the door gratings of the cave. In March 1989, nearly 400 Rhinolophus ferrumequinum were spotted, as well as hundreds of Miniopterus schreibersii, and tens of Myotis. In November 1989, between 14,500 and 15,000 Miniopterus schreibersii, nearly 200 Rhinolphus ferrumquinum, and several large Myotis specimens were noted.

12. "Manailovata Peshtera," near the village of Ribnovo in the Gotze Delcheve area.

The cave is approximately 1 km long. A stream flows through it. In the course of numerous visits made from 1958-1988, thousands of bats were reported, among which Miniopterus schreibersii dominated. In October 1988, 1200 Miniopterus schreibersii were reported. In October 1989, several thousand Miniopterus shreibersii were observed flying out of the cave in the early evening hours.

13. The bat cave near the village of Yantra, between the towns of Sevlievo and Dryanovo.

The cave is nearly 50 m long and has two cavities. During May 1989, nearly 5600 large Myotis were present, some of which were with newborns. The cave is visited regularly; fires are lit and bats are destroyed. Protection is urgently needed as the colony is extremely vulnerable.

The following caves and other sites, like those listed above, are inhabited by sizable bat colonies. However, they are not of primary importance because either (a) the bat colonies are not readily accessible due to steep cave entrances or other impediments, or (b) the number of bats extant is not high.

* 14. "Toplya," in the village of Golyama Jelyasa in the Lovech region.

During one visit in October 1989, 3000 Miniopterus schreibersii and considerably smaller numbers of 3 species of Rhinolophus and large Myotis were reported.

* 15. The water-eroded precipice "Drunchi Poopka," near the village of Melnitsa in the Topolovgrad area.

Colonies were spotted in August 1970, March 1971, and November 1989, and the existence of 1200 to 4000 Miniopterus schreibersii, and from ten to several hundred large Myotis was established. The bats dwell in the 22-meter deep precipice, and are essentially inaccessible. Visitors are extremely infrequent, and consist for the most part of speleologists.

16. "Devetashka Peshtera," between the trains stations of Levski and Lovech.

During September 1989, 2000-3000 Miniopterus schreibersii, approximately 30 Rhinolophus ferrumequinum, several tens of Vepertilio pipistrellus, a single Rhinolophus hipposideros, and a single Myotis were reported here. The bats are virtually invulnerable due to this large cave's high arches, which reach a height of 40-50 meters.

* 17. "Haidoushkata Peshtera," near the village of Devnitsa in the Cherven Bryak region.

This pattern of habitation in this cave is highly variable. In February 1989, bats were completely absent. In April 1989, researchers counted 5000 to 5200 Miniopterus schreibersii, an individual large Myotis, and an individual Rhinolophus hipposideros. On another visit in December 1988, up to 250 Rhinolophus euryale and other species represented by single individuals were found.

18. The cliff crevices resembling block-like formations near "Taouk-liman," north of Cape Kaliakra, Balchik.

A colony of about 100 Rhinolophus ferrumequinum dwells in the crevices. This colony is essentially invulnerable.

* 19. "Morovitsa," near the village of Glojene, Teteven.

The great quantities of guano found in the depths of the cave indicates the periodic habitation of large colonies. The presence of the following species was confirmed through the use of mist nets: Rhinolophus ferrumequinum, Rhinolophus euryale, Vespertilio serotinus, the two species of large Myotis, and Miniopterus schreibersii.

20. "Bozhkova Doopka," near the village of Krivnya in the Rasgrad region.

In April 1988, 300-400 Rhinolophus euryale were reported. A March 1989 visit found several hundred Miniopterus schreibersii, around 200 average Rhinolophus, and single representatives of Myotis emarginatus, Myotis capaccinii, and Myotis bechsteinii.

21. "Yamata," a precipice located behind the restaurant "Lednika" on Bratsa Mountain.

In November 1988, 55 large Myotis were found to be hibernating in the 45-meter deep precipice.

* 22. "Gininata Peshtera," near the village of Sadovets in the Pleven region.

In July 1988, nearly 1500 Miniopterus schreibersii, approximately 100 Myotis capaccinii and 50 average Rhinolophus, and several large Myotis were observed.

In December 1988, nearly 50 Miniopterus schreibersii, 2 Vespertilio serotinus, about 20 Myotis capaccinii, 2 Plecotus, and an individual Rhinolophus hipposideros were seen.

23. The water cave "Mandrata," between the villages of Chavdartsi and Alexandrove in the Lovech region.

In July 1988, 2000-3000 Miniopterus schreibersii and approximately 20 Rhinolophus ferrumequinum were reported.

In January 1989, around 60 Rhinolophus ferrumequinum and 15 Rhinolophus hipposideros were reported.

24. "Boskite," near the village of Mramor in the Topolovgrad area.

In October 1988, a colony of nearly 500 Miniopterus schreibersii was observed. In February 1989 no bats were observed. In 1971, local inhabitants either chased or killed nearly 800 Rhinolophus blassi. In the years 1958-1970 a significant colony of Myotis emarginatus, ranging from tens to hundreds of individuals, was observed around the entrance area. Bats have either been chased or killed a great many times in this cave.

25. "Kaleto," near the village of Mladezhko in the Strandzha Mountain region.

In June 1989, a colony of Miniopterus schreibersii was identified. During summer visits, colonies of several tens of Miniopterus schreibersii and Rhinolophus ferrumequinum, as well as average Rhinolophus, were observed.

During the winter, individual hibernating average Rhinolophus were found. The cave is frequently visited by tourists and treasure hunters. As a consequence, the existence of large colonies of bats is impossible.

* 26. The southern underground cave near the cape Maslen Nos, southwest of Sozopol.

This cave can be entered only through swimming or with a boat. It is inhabited by thousands (between 5000 and 8000?) of Miniopterus schreibersii, and by large Myotis.

During the last visit, in October 1989, 3000 Miniopterus schreibersii were counted, as well as several tens of large Myotis. The cave is very rarely visited. Consequently, the bats are virtually invulnerable.

27. Karaultash, a cliff approximately 1.8 km from the cape Maslen Nos, Bourgas region.

During the summer months, this cliff is inhabited by a mixed colony of approximately 500 Myotis emarginatus, and average Rhinolophus. The bats reproduce in the half-lit and windy openings of the crags. The colonies are extremely vulnerable.

* 28. "Lyastovitsata," near the village of Glojene, Teteven.

This wide cave has an abundant population of bats. Nearly 900 large Myotis and at least 300-400 Miniopterus schreibersii, 50 Rhinolophus ferrumequinum, 30-40 average Rhinolophus, and 10 Rhinolophus hipposideros were observed here.

During other visits, up to 80 large Myotis, 73 Rhinolophus ferrumequinum, and 12 Rhinolophus hipposideros were counted.

29. Zandana, near the village Ploski in the Sandanski area.

This is a semi-dark, narrow, tall slit or crack, with a horizontal floor set between craggy columns. In May 1988 there were 350-400 Rhinolophus ferrumequinum present. Two weeks later, 150-200 of the same species were sighted. The bats of Zandana are virtually invulnerable.

* 30. "Sedlarkata," near the village of Rakita in the Pleven area.

This aquatic cave is nearly 1100 meters long. It is difficult to visit without diving gear. At the beginning of the cave, and somewhat later in the interior, it is necessary to swim through a number of underground pools.

In July 1988, 800-1000 Miniopterus schreibersii, 20-30 Rhinolophus ferrumequinum, and approximately 20 Myotis daubentonii were seen. Special measures for the protection of these bat populations are necessary.

31. "Kalenska Pesht," near the village of Kalen, north of Mesdra, in the Vratsa area.

Entry to this cave is illegal as it is used as a water source.

During visits conducted in March of 1988 and 1989, 400-500 Miniopterus schreibersii, approximately 20 Rhinolophus ferrumequinum, and a single Rhinolophus hipposideros were observed.

During the second visit, approximately 260 Miniopterus schreibersii and 75 Rhinolophus euryale, 13 Rhinolophus ferrumequinum, 6 Rhinolophus hipposideros, and 2 large Myotis were present.

32. "Czarskata Peshtera," near the village of Belyakovets, Veliko Turnovo.

A March 1988 visit found approximately 1600 Miniopterus schreibersii and 20 Myotis daubentonii. Today the cave has been blocked and is used for commercial purposes. There is a slight possibility that the bats can enter it through a several hundred meter-long opening that connects the cave with its source.

33. "Kalna Mutnitsa," between the villages of Glavatsi and Byali isvor in the Mihailovgrad area

In the years 1965-1971, colonies containing up to 1000-1500 Miniopterus schreibersii, 250-300 hibernating Rhinolophus ferrumequinum, and single representatives of four other species were observed.

In July 1988, a colony of around 2500 Miniopterus schreibersii was observed, with several tens of large Myotis among them.

* 34. "Mishin Kamuck," near the village of Gorna Looka in the Mihailovgrad area.

In April 1988, observers counted nearly 9000-9500 Miniopterus schreibersii, nearly 50 Myotis blythi, around 10 Rhinolophus hipposideros, and approximately 20 average Rhinolophus. In December 1988, 13 large Myotis and a single Miniopterus schreibersii were reported.

* 35. "Soohi Pech," near the Orshets train station, Belogradchik.

In April 1988, a colony of 7500-8000 Miniopterus schreibersii, single representatives two species of Rhinolophus, and individual large Myotis were observed.

In December 1988, individual Rhinolophus ferrumequinum and Miniopterus schreibersii, as well as 15-20 Myotis capaccinii were seen. Similar data emerged from a January 1991 visit. The large quantities of fresh guano toward the back of the cave indicate that large colonies use the cave during the warm seasons.

This cave has a perpendicular entrance 10-12 meters high, and can only be visited by well equipped speleologists or cave hobbyists. Nearly 300 Rhinolophus ferrumequinum were found in a side gallery during the summer. In a winter visit, at least 100 of the same species, as well as individual large Myotis and Rhinolophus hipposideros, were observed.

* 37. "Bozhiyat Most," near the village of Lilyache in the Vratsa area.

The cave is located at a height of 9-10 meters on the wall of a cliff arch known as "God's bridge." The climb is very difficult. The cave is nearly 100 meters long. In July 1958, a colony of several thousand Miniopterus schreibersii and large Myotis was located. During subsequent visits, small groups of Miniopterus schreibersii and Rhinolophus ferrumequinum have been sighted. The quantities of guano indicate that the cave is periodically visited by large colonies of bats.

38. "Kecedzhiytsa," near the village of Melnitsa, Topolovgrad.

During visits in August 1970 and March 1971, a colony of 150-200 Rhinolophus ferrumequinum was reported. No bats were found in October 1988.

39. "Kolibata," near the village of Belidyehan, 25 km northwest of Sofia.

In August 1955, a colony of 600-800 Miniopterus schreibersii and several tens of large Myotis inhabited this cave. In August 1989, a colony of 60-80 of the same species was reported. Fires are periodically lit in the cave by visitors. As a result, the colony has been unable to reestablish itself at its 1955 (or prior) level. Individual bats of the genera Plecotus and Rhinolophus have been found to hibernate.

* 40. "Dyavolskoto girlo" ("the Devil's thought"), near Trigrad in the Devonsko area in the Rhodopes.

In June 1977 around 400 Miniopterus schreibersii were observed. In March 1989, nearly 10,250 bats of the same species were observed. The cave has been developed and is heavily visited by tourists. However, they do not appear to disturb the bats.

41. "Karnata Peshtera," near the "Yagodisnskata Peshtera," near Devonsko in the Rhodopes.

Amateur speleologists have reported the existence of large colonies of bats using the cave for hibernation.

42. "Urushkata Maara" near the village of Krooshoona, Lovech.

During visits in 1958, 1960, 1966, and in subsequent years, researchers found colonies of between 2000-6000 Miniopterus schreibersii, lesser numbers of large Myotis, and individual bats of other species. In March 1989 20-30 Miniopterus schreibersii and 3 Rhinolophus ferrumequinum were reported.

43. "Tumnata Doopka," near the village of Resselets, Chervenbregg.

Colonies of several hundred bats have been observed on numerous occasions. Their numbers are difficult to determine due to the inaccessibility of their dwelling places (they are some 30 m above the cave floor). The following species have been confirmed: Miniopterus schreibersii, large Myotis, Myotis emarginatus, and, during the winter, individual Rhinolophus ferrumequinum.

* 44. The cave near the village of Emen in the Veliko Turnovo area.

Various attempts to commercialize or develop the cave have been made and abandoned. The cave is in a decrepit condition. Furthermore, it is visited frequently by tourists.

Around fifty Miniopterus schreibersii, as well as 29 Rhinolophus ferrumequinum, and individual bats of other species were found during a January visit.

During an October visit, around 100 Rhinolophus ferrumequinum and 200-220 large Myotis were observed. The quantities of guano indicate that sizable colonies of bats dwell in this cave during certain seasons.

45. "Vodnata Pesht," near the village of Lipnitsa in the Botevgrad area.

During the years 1960-1973, and at numerous times since, colonies of 80-100 Rhinolophus ferrumequinum and up to 300-400 Miniopterus schreibersii have been reported. Speleologists built a cabin near the cave in 1980 to serve as a training base. They have reported finding on occasion small groups of up to 20 bats.

46. "Footyofska Peshtera," near the village of Carpachevo, Lovech.

In September 1960, several individual bats were found to hibernate here. However, the considerable amount of fresh guano present indicates that this cave is periodically inhabited by a colony of several hundred Miniopterus schreibersii.

* 47. The precipice "Soohata Drunchidoopka" between the villages of Ostrem and Mramor, Topolovgrad.

This precipice is nearly 100 meters deep. At its bottom are two chambers that contain considerable quantities of guano.

In August 1970, several tens of Miniopterus schreibersii and an equal number of Rhinolophus were observed. In November 1989, the entrance was found to have been filled in with thorny shrubs. Shepherds had filled it to prevent their flocks from falling in. Consequently, no bats were found. If free access is once again established, the bat colonies will probably return to their old habitat.

* 48. The precipice-cave "Lednitsata" in Zlosten, near the town of Kotel.

This structure is 1142 m long and 242 m deep from the entrance to the cave's bottom. In September 1970, between 1500-1700 Miniopterus schreibersii were reported. In September 1989, only 520-550 Miniopterus schreibersii and two Myotis blythi were found. The quantities of guano indicate that large colonies of bats regularly inhabit this cave. The deeper areas of this cave require the use of mountain climbing gear. Consequently, no special protection measures are necessary for the time being.

Documentation is available concerning nearly eight hundred other caves, precipices, and artificial mineshaft galleries across the country. These sites serve as dwelling places for individual bats, for tiny colonies that inhabit them inconsistently or occasionally, and for larger colonies that occasionally use them as stop-off points for one or two nights during their migratory flights.

Many of the bat species that inhabit caves can also be found outside caves, particularly during the warm seasons (Miniopterus schreibersii, which is closely associated with caves and dwells within them almost exclusively, is an important exception). The species of the genus Rhinolophus can be observed dwelling in man-made structures, on cliffs, etc. Colonies of 200-300 Myotis emarginatus can at times be found alongside the Rhinolophus.

During the hot months, Vespertilo serotinus habitually occupies cracks in human dwellings or construction sites, as well as craggy cliffs and other natural niches. This also holds true for the two Plecotus species. From June to August the two large Myotis settle in the warm and well ventilated domes of cave entrances and arched cliffs. These two species sometimes choose to inhabit human structures, settling in clock towers and other suitable sites. Members of the genus Nyctalus dwell exclusively outside caves. They reside primarily in tree hollows. However, during the spring and autumn they will settle for brief periods of time in hidden corners of human habitats. In rare instances, colonies of Nyctalus noctula will occupy cracks and chinks in human dwellings for the entire summer season (this occurred on one occasion at the Ministry of Interior's building in Sofia).

Areas of Special Ecological Significance

The biological requirements of the bats determine their daily and seasonal habitats, including those territories of special ecological significance. Bats are found in all regions, from arid and semi-desert areas to farmlands, deciduous and coniferous forests, and the subalpine belt of the high mountains.

The distribution or dispersion of large colonies depends, more than anything, on the existence of caves and other underground chambers that are large in volume, meet particular microclimatic requirements, and are protected from human visitation and aggression. The altitude of the cave undoubtedly plays an important role in establishing its temperature, and in ensuring the presence of the fauna, primarily flying insects, that serve as a food source for the bats. Thus the large colonies inhabiting the caves listed above are between 5 and 800 meters above sea level. At higher elevations, the colonies are few and tiny, or the bats occurs as individuals.

The protection of bat dwelling caves that are continuously or occasionally inhabited is the most important requirement for the preservation of bats in Bulgaria. Rare species, species that occur as individuals, and non-cave dwelling species can be protected through information dissemination, educational activities, and in some specific instances through protection of their territories or habitats (such as hollows in trees or trunks and other temporary dwellings). Information dissemination can also help protect those bats that either dwell or hibernate in caves that cannot, for whatever reason, be given protected status.

Sensitivity to Human Activity

Comparison of cave dwelling bat populations in Bulgaria for the periods 1955-1971 and 1988-1992 indicates a considerable decline. This decrease has been estimated at between 20 and 40 percent. Observation and analysis of the data indicates that the determinant factor in this population decrease is the frequent disruption, violence, and destruction perpetrated by visitors. Researchers from Central and Western Europe have come to the same conclusion.

The number of visitors to caves has greatly increased over the last 20-30 years. During the past 3 years, however, this number has been reduced. Active professional and amateur speleologists number several thousand, while unorganized tourists numbers in the several hundred thousands. The caves located in the Lakatnic cliff massif are a case in point supporting the above contention. This area is located 60 km north of Sofia. Thirty to thirty-five years ago, some 200-250 bats belonging to 9 species hibernated within these caves. The number of raucous groups setting up camps and lighting fires inside the caves has subsequently increased greatly. As a consequence, there are presently no more than 15-20 bats of 3 to 4 species hibernating in the caves. The survey methodology used was the same for both time periods. Conversely, the Golak mine shaft (#4 above), which had smaller bat populations 20 to 25 years ago, has shown a considerable increase in its population during the past 10-12 years. This is a result of reduced visitation and disturbance (the village of Golak has itself had a reduction in its population).

Only tiny groups or individual bats enter hibernation caves that have been commercialized or converted into tourist centers (caves such as "Magoora," "Ledenika," "Snejana," "Batcho Kiro," and a few others). However, the large hibernating colonies that dwell in the "Diavolskoto Girlo" (#40), the "Yagodinskata Peshtera," (near #41), and in the "Orlova Chooka" (#11) have been protected. Comparisons between current populations and those present prior to commercialization indicate that bats in the caves that have been developed or commercialized (#s 10, 23, 34, 44) have been massively eradicated. There are also cases where the caves have not been developed, but the bats are frequently disturbed and even destroyed (#s 9, 17, 20, 22, 24, 25, 37, 39, 45).

It is important to note that bat population numbers have not declined appreciably over the past decade in caves 15 and 26, where entry is difficult.

The hypothesis that bat populations have been reduced due to the effects of pesticides on their food base is unproven. Special studies of the quantities on nocturnal flying insects have not been carried out. Even if such studies had been carried out, we lack baseline data with which to compare them: no data on these insect populations are available for the period prior to the onset of chemical pesticide use in farming and forestry. However, indirect observations indicate that the use of insecticides and other chemicals has not had a visible impact on the population of bat colonies.

Large bat colonies can exist in highly developed, intensive farming areas as long as their habitats are not frequently visited (cave #1 is an example). No bats have been found to have been killed by poisons or pesticides. On the contrary, in all cases the carcasses have shown evidence of direct extermination by physical blows or through the effects of hot stinging smoke.

According to our analysis, the factors that negatively affect bat population can be grouped as follows:

1. Highly intensive negative factors

a. Fires in caves or cave entrances, especially during bat reproductive stages (end of May through middle of July).

b. Direct destruction of bat colonies with sticks, usually in combination with the lighting of fires inside caves.

c. Noise in caves, particularly startling shouts or sounds from other sources. If noises are frequently repeated, the bats will desert the cave.

2. Negative factors with average effects

a. Artificial illumination of colonies. This is almost always accompanied by noise.

b. Development of caves into tourist centers or conversion to commercial use. Construction itself, as well as the subsequent uses, are always accompanied by the above factors.

c. Enclosure or outright closing of cave entrances, and demolition of cave entrances for quarries. These cases are still rare, and fortunately have not affected the bat population density of the country as a whole.

d. Destruction of tree hollows. This adversely affects species, such as those in the genus Nyctalus, that regularly inhabit tree hollows. Of 12-13 tree hollows in the vicinity of Sofia inhabited by Nyctalus noctula in the years 1955-1958, only 4 remained during 1971. The others had been cut down.

3. Negative factors with slight effects

a. The effects of industrial pollution, chemicals, and pesticide use. As previously noted, we lack specific data as to these effects. It can be assumed a priori that chemicals have a negative effect on bats. It appears, however, that the effects are neither rapid nor drastic.

Known Dangers

The future threats to Bulgaria's bat populations are essentially the same as those actively present today. However, the most imminent dangers faced by the bats, such as disruption, chasing away, and outright destruction by visitors, have probably been reduced in the last 3-4 years. A number of factors might explain this, among them the economic recession, greater public interest in politics, and the possibility of starting private enterprises. These may have veered interest away from tourism. These factors have also resulted in a drastic decline in visits to the developed caves, as reflected in reduced ticket sales and fewer visits to vacation cabins. We have reason to believe that this pattern also holds true for "non-developed" caves when current visitation rates are compared with those of the 1970s and early 1980s.

At the same time, increasing private business initiatives could once again focus on the caves, and lead to the conversion of some of them into restaurants, storage facilities, and other commercial enterprises. This would cause bats to abandon caves or even to go extinct. This would also result in the destruction of priceless archeological and paleontological data, as well as the impairment of natural beauty. Consequently, commercial development of caves should not be allowed.

Bats are also threatened by the extraction of guano from some caves. Over the last 20 years, this practice has been virtually abandoned in Bulgaria. However, with the return of private farming, it is likely to resume. It is im-portant that decisions about guano extraction be made on a case-by-case basis following a study of the status of the colony, its seasonal habits, and concrete measures that can be taken to protect the bats.

Sites Containing Representatives Samples of Biological Diversity

In the case of bats, determination of such areas would be artificial and inexpedient. We recommend that measures be taken to protect the most important caves. This would to a great extent ensure the protection of the large bat colonies in Bulgaria, as well as their territories and the nocturnal insects upon which they depend. In order to protect the non-cave dwelling species, or those that only temporarily inhabit caves, we recommend a public awareness campaign and the establishment of fines to serve as penalties.

Recommendations

1. The most important caves (#s 1-13 on the above list), as well as other caves on the list that support the larger and more vulnerable colonies, should be placed under protected status. Caves 20, 22, 24, 28, 35, 39, 42, and 47 should be given highest priority for such protection. Some of these are marked with the "*" symbol, indicating that they have protected status. However, actual measures for their protection, and in particular the protection of the bats, have not been undertaken.

In addition to legislative recognition, a number of specific measures must be taken to protect the caves. Strong steel doors with gratings to permit the bats easy access need to be erected. Access to cave entrances needs to be limited. Built-in steps, wooden bridges, ladders, and other constructions that provide easy access to the bat colonies need to be removed. Cave "instruments" used to destroy bats (e.g., sticks) need to be cleared away, and steps taken to prevent the breakage of stalactites. Materials that have been abandoned in the caves by visitors and that can easily be lit for fires (e.g., straw, rubber, plastics) should be removed. The activities of visitors need to be controlled (by, for example, temporarily barring visitors to caves, particularly during the bats' reproductive or hibernation phases). Appropriate periods for guano collection need to be determined.

2. The protection of bats should be pursued through a public awareness campaign. More precisely, information concerning pertinent legislative acts and reasons for the protection of bats and their habitats should be disseminated. All available media should be used and the campaign should be geared to all levels.

3. The legal measures that have already been enacted should be applied and enforced. At present, not one individual has been penalized for the destruction of bats, their habitats, or their ecosystem. It is important that when such penalties are invoked, they be announced in the mass media.

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