Ábrahám Levente: Biomonitoring a Dráva folyó magyarországi szakasza mentén 2000-2004 - Natura Somogyiensis 7. (Kaposvár, 2005)

Dombi, Imre: Bat monitoring along the Drava River (Mammalia: Chiroptera) - Denevér-monitoring a Dráva mentén (Mammalia: Chiroptera)

DOMBI I.: BAT MONITORING ALONG THE DRAVA VALLEY 155 distance, too. The small ratio of Myotis sp., Plecotus sp. and Barbastella sp. can be due to their rarity and also their hard delegability. Neither species, nor genera were identifiable in 11 % of all cases. Point counts sampling of the Daubenton's bat {Myotis daubentoni) and pond bat {Myotis dasycneme) was carried out in Őrtilos, Vízvár and Babócsa. Data showed great fluctuation comparing the years. In some cases it can be explained with the drastic change of environment, for example in Babócsa the dry conditions of backwater of the Drava in August, or the migration of parts of colonies. According to the data collected so far the best sampling area is the backwater of the Drava in Babócsa. Also the pond bat (Myotis dasycneme) was detected the most often here, which fact justifies the good habitat features of the area. The species was detected the most numerously in July 2002 (200 ind. within 1 hour). The situation is the worst in Őrtilos. The number of Daubenton's bat {Myotis daubentoni) is the smallest here and the pond bat {Myotis dasycneme) only occurs rarely, too. The reason for that seems to be the small number of prey due to the great current of the river. 18 clerical buildings of 14 settlements of the research area are monitored. Bats live or lived in all observed buildings. Five species were indicated. According to their frequency, they are respectively: serotine bat {Eptesicus serotinus), grey long-eared bat {Plecotus austriacus), greater mouse-eared bat {Myotis myotis), Nathusius' pipistrelle bat {Pipistrellus nathusii), common pipistrelle {Pipistrellus pipistrellus). Four steady colonies are known, in the other places bats are only present in small numbers and just occasionally. The most significant colony that is of greater mouse-eared bat {Myotis myotis) is in the Catholic church in Babócsa, but the number of its individuals unfortunately decreased from 150 to 70-80. Hopefully, it is only about migration to another site, since an increase was recorded in the other significant colony at Somogyudvarhely at the same time. Here there are 40-50 individuals. The grey long-eared bat {Plecotus austriacus) rarely has a big colony, though it was detected almost everywhere. A 25-30 individual parent colony lives in Surd. The biggest colony of the serotine bat {Eptesicus serotinus) with 60-80 individuals can be found in Zákányfalu in the Catholic church. Discussion The monitoring project having been carried out since 2000 revealed the fact that the Drava between Ortilos and Babócsa has a very significant bat-fauna. 17 species of bats were indicated in the four sampling areas that takes out 61 % of the national bat-fauna. The detection of three endangered species Barbastelle bat {Barbastella barbastellus), Bechstein's bat {Myotis bechsteini) and the pond bat {Myotis dasycneme) with strong reproducing stocks are of special importance. All the European stocks of the three species are crucially endangered, because the old forests having served as their natural habitats are extinct. Since reproducing colonies live along the Drava the protection of their habitats is a cardinal duty. Interesting, but so far not proved the appearance of a new species in our country which is likely to be Plecotus macrobullaris. During the survey it is registered as Plecotus sp., and it was detected in Ortilos and Vízvár. During the monitoring it became clear that all our chosen methods should be applied simultaneously to receive accurate and reliable data on the bat colonies and to trace any changes. None of them on its own provide enough data neither in quality, nor in quantity concerning all the species. The other lesson that we learned is that still a lot of intense research years are needed even to gain result on the original state, since after five years new species occurred in the given sample areas.