Ábrahám Levente (szerk.): Válogatott tanulmányok IX. - Natura Somogyiensis 24. (Kaposvár, 2014)
Szűcs D. - Kitti Horváth K. - Horváth Gy. F.: Comparing small mammal faunas based on barn owl (Tyto alba) pellets collected in two different lowland landscapes
Natura Somogyiensis 24 305-320 Kaposvár, 2014 Comparing small mammal faunas based on bam owl (Tyto alba) pellets collected in two different lowland landscapes Dominika Szűcs, Kitti Horváth & Győző F. Horváth University of Pécs, Faculty of Natural Sciences, Institute of Biology, Department of Ecology, H-7624 Pécs, Ifjúság u. 6., Hungary; e-mail: Szűcs, D., Kitti Horváth, K. & Horváth, Gy. F.: Comparing small mammal faunas based on barn owl (Tyto alba) pellets collected in two different lowland landscapes. Abstract: The composition of small mammal assemblages was analysed in two lowland landscapes (Drava floodplain, Győr basin) and was evaluated on three different spatial scales (meso-, microregions and local scale), based on bam owl pellets collected between 2006 and 2009. Altogether 273 pellet samples were collected from 41 settlements of the two regions during the four years of monitoring. The analysed 6978 pellets contained 17214 small mammal individuals. The distribution of the relative abundance of small mammal taxa was evaluated as well as the correlation of frequency order on a meso- and microregional scale in the comparison of the two lowland areas. The food niche parameters of bam owl were calculated on a local scale, regarding the breeding pairs. We investigated three null hypotheses: the distribution of species frequency values is homogeneous between two landscape areas (H01); there are no significant differences in the rank of frequencies (H02) in meso- and microregional scale; and niche parameters of the bam owl do not show difference between two landscapes (H03). The first null hypothesis had to be rejected in several cases of small mammal taxa. The rank correlation of species frequency and the homogeneity test of total species pool of two investigated landscapes showed that the composition of small mammal fauna of the compared landscapes is basically the same, but the distribution of abundance was different between landscapes on both meso- and microregional scales. The statistical analysis of the niche parameters showed that the bam owl’s niche breadth did not differ between the Drava floodplain and the Győr basin. However, the niche overlap within each of the two mesoregions was higher than between them, and thus we rejected the third null hypothesis. This provides a further evidence that besides the species-specific hunting strategy, the regional differences of the quantitative relations of small mammals is also reflected in the dietary composition of the bam owl. Keywords: small mammal, relative frequency, spatial scale, landscape, Tyto alba Introduction The bam owl (Tyto alba) is the strigiform with the broadest worldwide distribution (Burton 1984, Taylor 1994). Bam owl breeding density has been studied in different areas of central Europe (De Bruun 1994, Poprack 1996) and the Mediterranean region (Fajardo 2001, Salvati et al. 2002, Martínez & Zuberogoitia 2004), moreover it is a well-known fact that the population levels of this owl species correlates with cyclic fluctuations of small mammals (De Bruun 1994, Taylor 1994). Thus the composition of its diet has been studied more extensively than in any other bird of prey (Everett et al. 1992).
