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

Szűcs, D., Horváth, K. & Horváth, Gy. R: Small mammal faunas

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mammal taxa (Spearman’s rank correlation). The relationship of abundance was tested by one-way analysis of variance (ANOVA) in both landscapes (microregions). In the case of one-way ANOVA test firstly, we examined variables for normality using Shapiro- Wilk test, and homogeneity of variances using Levene test. We used non-parametric Kruskal-Wallis median test when assumptions of ANOVA did not meet. When significant differences were detected in ANOVA or Kruskal-Wallis test, we employed LSD-test or Dunn's procedure for post hoc multiple comparisons (Zar 2010).

Local scale

We calculated food niche parameters in each local sampling plot (settlements), which represented a breeding pair. We used Levine’s measure (B{) to define the niche breadth of bam owls in each settlement:

n

2>2

i=i

where />, is the proportion of individuals found in or using resource state j. The resource utilisation overlap of bam owl was calculated by Pianka’s measure of niche overlap (Ojk) between two local sample pairs:

Ojk =

I pH?

where ptj and pik is the relative proportion of the ith prey in two samples (j and k) which mean breeding pairs of the involved settlements and n is the number of prey categories. We used independent Mest to compare means of niche breadth between two mesoregions. We employed one-way ANOVA with post hoc multiple comparison (LSD) to test the values of niche overlap within the Drava floodplain region and the Győr basin, and between the two landscapes.

Results

Evaluation of data in mesoregional scale

The analysed 6978 pellets contained 17214 small mammal individuals. According to the summarized data of the collected pellets samples during the four-year period, we defined the abundance and relative rate of small mammal taxa (Table 1). Species with relative frequency values over 1% regarding the rank of frequency were considered to be characteristic species in both mesoregions (Drava floodplain: S = 14, Győr basin: S = 12) (Fig. 2).

The common vole (Microtus arvalis) was eudominant in both landscapes, because this species is the main prey of the bam owl. Its frequency value constituted almost half of the total abundance in the Drava floodplain. The second in order was Apodemus spp. taxa (12.72%). The common shrew (Sorex araneus) had high proportion in the Győr basin and it was second in the order of dominance, so there were two dominant species