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

126 NATURA SOMOGYIENSIS Fig. 4.: Daily water levels of the Drava, measured at Barcs in May-July 2004 Actitis hypoleucos and Charadrius dubius population survey between 199-180 Drava river kilometres We attempted to do a complete population survey of Charadrius dubius and Actitis hypoleucos in the Hungarian-Croatian area of the Drava section between river kilometres 199-180 (cca. 650 ha). Population survey was done from both ashore and boat, completed with the walk-surveying of certain gravel shoals. Based on numbers of observed individuals, recorded pairs and incubating birds, nesting data of the studied species in 2000-2004 were found to be as presented in Table 6. Our data show that anually at least 32-48 pairs of Charadrius dubius and at least 5-15 pairs of Actitis hypoleucos occupied nesting territories in the studied area (Table 6.). It was found that territory occupation and nesting success was considerably affected by water levels of the Drava. For example, due to prolonged high water levels, Charadrius dubius nested also in ploughland environments adjoining the river in several locations. Flood waves arriving in June-July tended to wash away a significant proportion of clutches, and, in certain years, replacement clutches as well. Table 6.: Results of population survey between 199-180 Drava river kilometres in 2001-2004 Species Bélavári 99-193 river km Vízvár 192-188 river km Heresznye 187-184 river km Bolhó 183-180 river km Total Species 2001 C. dubius 8-10 pairs 15 pairs 8-10 pairs 4-5 pairs 35-40 pairs A. hypoleucos 1 -2 pairs 3-4 pairs 1-2 pairs 5-8 pairs A. hypoleucos 2002 C. dubius 9 pairs 20 pairs 4 pairs 3 pairs min. 36 pairs A. hypoleucos 3 pairs 4 pairs 3 pairs min. 10 pairs A. hypoleucos 2003 C. dubius 15 pairs 22 pairs 6 pairs 5 pairs min. 48 pairs A. hypoleucos 4 pairs 5 pairs 2 pairs 1 pairs min. 12 pairs A. hypoleucos 2004 C. dubius 4 pairs 19 pairs 4 pairs 5 pairs min. 32 pairs A. hypoleucos 2 pairs 8 pairs 3 pairs 2 pairs min. 15 pairs I