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Turkish Journal of Zoology

DOI

10.55730/1300-0179.3160

Abstract

In this paper, we investigated the relationship between the breeding parameters and food composition of the common barnowl (Tyto alba) comparing the outbreak and subsequent crash periods of the common vole (Microtus arvalis) as the barn owl’s main prey. For the analyses, data of 29 (2014 outbreak: 6, 2016 crash: 8; 2019 outbreak: 7, 2021 crash: 7) breeding pairs of barn owls were selected. First, we examined the differences between the breeding parameters (clutch size, number of hatchlings and fledglings), the main and alternative prey taxa (common vole and Apodemus genus), the two derived indices (trophic level index, Microtinae/Murinae ratio) between the given outbreaks and subsequent crashes as well as the cumulative data of the two demographic periods. In addition, we analysed the difference in rank-abundance distribution of prey composition comparing the outbreak and crash. We investigated the relationships between breeding parameters and demographic periods, the main and alternative prey taxa and the two derived indices using generalized linear mixed models (GLMM). The clutch size was significantly higher in both outbreaks than the crash periods, while the number of hatchlings and fledglings differed only between the second outbreak and crash period. Regarding the cumulative data of outbreaks and crashes, the values of all three breeding parameters were significantly higher in the outbreak period of the common vole. Our results highlighted the main prey role of common voles during the outbreak, as well as the importance of the Apodemus genus during the crash period. GLMM analysis supported that all three breeding parameters were positively determined by the ommon vole’s abundance in the diet of barn owls in outbreak and crash periods, while the reproductive output was positively influenced common by the frequency of the Apodemus genus as potential alternative prey in the crash period.

Keywords

Food composition, breeding parameters, common barn-owl, common vole, demographic period

First Page

54

Last Page

76

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