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

Fenyősi, László: Studies of avian communities along river Drava, between 2000-2004 (Aves) - Madárközösségek vizsgálata a Dráva somogyi szakasza mentén, 2001-2004-ben

FENYŐSI L.: STUDIES OF AVIAN COMMUNITIES 121 of the Drava from Ortilos to Drávatamási, is the Middle Drava Valley. The Drava reach below Drávatamási belongs to the Drava Lowland small region, whereas areas of the Bares Juniper Woodland are groupped with the small region of Eastern Inner Somogy. These small regions are characterised with moderately warm climate (with the annual mean temperature being around 10.0-10.5 °C ), and with precipitation amounts decreasing from the northwest towards the southeast (mean: 750 mm). Material and methods The investigation of birds (Aves) within "Drava Monitoring" has, from the beginning, focussed on several significant taxa and has meant various methods. We believe that the selected communities and taxa well represent the avian fauna of the area, and, in the case of long term investigations, can reflect changes in the status of habitats. The monitoring of passerine communities in the Ortilos-Zákány and the Vízvár sampling areas was done using the method of "double-visit fixed radius point count technique" (MOSKÁT 1986, 1987). Members of Passeriformes species, as well as representatives of Columbiformes and Piciformes were recorded. Among shoal-nesters, the characteristic, nesting communities of Charadrius, Actitis and Sterna species, not observable anywhere else in Hungary, were monitored. The method followed was specimen counts and recording pairs and families moving together, as well as, in case of colony nesters, the counting of nests and incubating individuals. Riparia riparia and Merops apiaster populations were monitored between river kilometres 198-133 of the Drava. In the case ofRiparia riparia the number of breeding pairs was calculated from counts of nest hollows, whereas Merops apiaster populations were recorded by individual counting. In recent years we have extended our surveys onto colonies found in Croatian Drava sections between river kilometres 236-198. On the Hungarian-Croatian river section between Bélavár (199 river km) and Heresznye (184 river km) migrating and overwintering populations of waterfowl are surveyed in January-March and October-December. Surveys are done primarily from boat, with species and nuber of individuals being recorded. In the Berzence Jalszina-meadow we use territory-mapping for investigating the nesting bird community. The open area is walked over 4-6 times in the nesting period, and the positions of individuals displaying nesting behaviour are fixed in a grid. The number of territories and nesting pairs can thus be determined. White storks are studied in 17 villages in the arwas between Ortilos and Szentborbás. Data recording inside the villages and in the outskirts is done in spring and in July, with parameters used in population surveys being recorded (HX, Hpa, HE, HPm, HPo, JZg, JZG, JZM, STD). Other faunal data are also continuously recorded in in monitoring areas, thus creating a faunal database. Results Monitoring passerine communities - Zákány sample area The sample area was designated in the outskirts of the vilages Zákány and Ortilos, in the floodland forest bordered by the railway line and river Drava (Fig. 1.). The survey was done in a 100 m radius circle in the case of 7 sampling points, and in a 100 m radius