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

Horváth, Győző, Molnár D., Németh Tamás - Csete Sándor: Landscape ecological analysis of barn owl pellet data from the Drava lowlands, Hungary - A Dráva menti gyöngybagoly köpetekből nyert adatok tájökológiai elemzése

HORVÁTH ET AL.: ECOLOGICAL ANALYSIS OF BARN OWL PELLET DATA 185 Fig. 1. Relationship between the proportions of dry, closed forests as potential habitats, and C. glareolus IS. araneus relative frequencies in the three studied Drava reaches Fig. 2. Relationship between the proportions of natural grasslands as potential habitats, and С suaveolens IM. sipcilegus relative frequencies in the three studied Drava reaches Based on patch patterns the area designated in the lower Drava section was significantly different from the two regions selected in the upper reach, although this difference could not be statistically proved. As seen from the homogeneity tests, among species that differed significantly in their percentages in the the entire reaches, it was the common shrew that had similarly high G-values for its habitat, i.e. for closed, dry forests. As shown by G-tests performed in order to compare patch compositions and prey compositions of bam owl hunting areas and the corresponding Drava reaches, in the case of several nesting locations the proportions of both certain patyh types and their characteristic small mammals differed significantly from values obtained for the larger-scale areas. These relationships are seen primarily in species that are heavily preyed upon by the bam owl. We have shown in our earlier investigations that the sizes of various habitat patches within the hunting range of the barn owl often determines the frequency values of small mammals calculated from pellets, which can be proved by regression analysis (HORVÁTH et al. 2003). In most cases, the correlations between proportions of patch types and prey species having striking homogeneity-test G-values could be clearly shown by regression analysis in the present study, too, consequently, barn owl pellet