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 DRÁVA VALLEY 147 3. Surveying building-dwelling colonies It has a very crucial part in monitoring, since many species live exclusively in buildings. Most of them are parent-colonies, thus keeping track of them well indicates the changes occurring around them. During the project we mainly concentrated on clerical buildings, because previous studies showed that most of building-dwelling colonies live in the towers or attics of churches. Throughout the survey churches are observed and characterised once a year following the same aspects of data collection. The characteristics of the buildings as habitats, the detected species and number of individuals, presence of other species (barn owl, pigeon, mart, etc.), and changes compared to previous years (e.g. locked window) are recorded during the assignment. A total number of 19 buildings were involved in the monitoring The observed settlements are as follows: Ortilos, Zákány, Surd, Gyékényes, Nemespátró, Porrogszentkirály, Csurgó, Berzence, Somogyudvarhely, Bélavár, Vízvár, Heresznye, Bolhó, Babócsa. Features of sample areas 1. Ortilos Reasons for the choice: Drava enters Hungary at this point, so impacts from abroad are noticed the earliest here. Nevertheless at Zákány it leaves Hungary again and flows down in Croatia, where it may face other effects. Therefore the Ortilos part can function as a control-area, where the probable negative effects on Drava River can occur in a different way than at the part below Vízvár. General classification: Well-confined area. We can meet variable surface features, from the mainstream to the distributaries, from gravel-pit lakes, to railway embankments. The ligneous vegetation mainly consists of middle-aged forests. Older forests are situated only along the distributaries continuously filling-in and above the railway. The main species are white willow (Salix alba), poplars (Populus sp.), Hungarian ash (Fraxinus angustifolia), common oak (Quercus robur). Above the railway highland species can also be found, such as beech (Fagus sylvatica), sycamore maple (Acer platanaoides), hornbeam (Carpinus betulus). Lack of old stocks is a disadvantage concerning the bats, since the number of roosting sites is restricted. This fact is also proved by the collected data. Because of the lack of tree-holes the bat-stock on the area can only be reported as low based on previous research. The gravel-pit lakes that are filling in are used as a foraging site by those bat species which hunt mostly above water and other open areas, such as the noctule bat (Nyctalus noctula), the Daubenton's bat (Myotis daubentoni), and the common pipistrelle (Pipistrellus pipistrellus). There is a relatively large area with treeless, grove-flora, part of which are covered with reed and other waterindicator vegetation. These are foraging sites, too. Methods applied: capture, sampling with detectors - point count and line transect and method. 2. Lankóci forest Reasons for the choice: The area is a bit further away from Drava, however with its old oak and hornbeam forest represents a very precious habitat. General classification: The old hardwood and softwood stocks offer very good roosting sites for bats. The chosen area is covered with a very versatile vegetation, from the stagnant water sedge and alder-swamp to the oak forests. This high level of diversity can ascertain the different roost demands of each bat species. Diverse vegetation also supplies the animals with a steady and dependable nutrition base. Paths and openings are well utilised by bats during hunting, thus observations having been carried out with