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

130 NATURA SOMOGYIENSIS ments are being continuously reproduced, the rate of occupied nests can be higher than 60%, at least 75% according to our estimation. The monitoring of birds in the Jalszina-meadow at Berzence The sample area is located near the village Berzence, in the Jalszina-meadow, covering 34 ha (Fig. 8.). During area surveys, the observed bird species and their numbers were recorded, and the position of individuals displaying territorial behaviour were fixed in a grid. The nesting bird community of the area was determined by evaluating the recording sheets and by marking the boundaries of territories. Although the number of samplings was less then what iusual for this method, this fact was balanced by the perfect observability of the meadow, by its relatively small extent, and the smaller (2x50m) stripe width applied. During the recordings in the successive years from 2001 to 2004, the number of bird species observed was 33, 24, 30, and 36, respectively. Of these, the number of species surely nesting in the area was 10 in 2001 (32 pairs), 12 in 2002 (35 pairs), 15 in 2003 (42 pairs), and 13 in 2004 (46 pairs) (Table 10.). The number of breeding pairs and density values are specified in Table 10. From Table 10 it appears that the nesting bird community of the area was made up of 10-15 species in the various years. Among these, the species with the highest densities were usually Alauda arvensis, Saxicola torquata, Miliaria calandra, and Acrocephalus schoenobaenus, Emberiza schoeniclus, Locustella naevia. In 2003, and especially in 2004, extensive patches had long lasting water cover. This is what may have caused the appearance of species like Anas sp., Fulica and Gallinula for breeding, and also a significant change of density in certain species (e.g. Saxicola rubetra, Acrocephalus schoenobaenus). It is notable that the 3rd-4th highest density value in the studied years was reached by Locustella naevia. Table 11 includes the complete list of birds observed in the area (68 species). Among species listed in Table 11, we assume that Ixobrychus Fig. 8.: Location of the sample area in the vicinity of Berzence