Diet structure of Tengmalm’s owl (Aegolius funereus) in the Ore Moutains in 2014-2015: the effect of laying date on the presence of Apodemus mice and Sorex shrews

The study of feed ecology of Tengmalm s owl has been progressing at the department of ecology at the Environmental Science of the Czech University of Agriculture in Prague since 1999. Feed is examined in Loučen part of the area of the Ore Mountains, which is destroyed by imisions, in the surrounding of Fláj barrier with the extent of 70 km2. Researching part is situated in the northwest area of the Czech Republic. My part of the research of Tengmalms owl s feed was progressed in 2014-2015 and carried out by the method of analysing of pellets and residues which are from nesting boxes. The total amount of the analysed prey animals was 1608 individuals from 32 samples, from which there were 1575 mammals (Mammalia) (97,9 %) and 33 birds (Aves) (2,1 %). In 2014, 6 samples were analysed. In these, 259 pieces of prey were determined. The following year it was 26 samples, in which 1349 pieces of prey were determined. The substitution of mammals had this composition in 2014-2015: Apodemus sp. - 52,8 %, Microtus agrestis - 25,1 %, Microtus sp. - 8,0 %, Sorex araneus - 3,0 %, Clethrionomys glareolus - 2,7 %, Microtus arvalis - 2,0 %, Muscardinus avellonarius - 0,6 %, Sorex minutus - 0,5 %, Micromys minutus - 0,1 %. The substitution of birds was following: Turdus philomelos - 0,4 %, Phylloscopus sp. - 0,4 %, Aegolius funereus - 0,2 %, Erithacus rebecula - 0,2 %, Pyrrhula pyrrhula - 0,2 %, Fringilla celebs - 0,1 %, Parus major - 0,1 %, Anthus trivialis - 0,1 %, Carduelis cannabina - 0,1 %, Ficedula sp. - 0,1 %, Garrulus glandarius - 0,1 %, Regulus regulus - 0,1 %, Sylvia atricapilla - 0,1 %, Turdus merula - 0,1 %. The first aim was to classify the substitution of Shrews and Apodemus mice in the relation to the time of nesting of Tengmalms owl. Big difference in share of Apodemus mice and Tengmalms owl was given in feed of Tengmalms owl in following 2014-2015. In 2014 Apodemus mice were 19,3 % of feed while they were 59,4 % in 2015. In 2014 Apodemus mice were 18,8 % food of Tengmalms owl, while it was 3,9 % in 2015. Next it was found out that in 2014 substitution of neither Apodemus mice (Apodemus sp.), nor Tengmalms owl in feed of those ones didnt change during their nesting so much, the influence of the time of their nesting wasnt determined. During nesting time in 2015 share of Apodemus mice in feed of Tengmalms owl was brought down, it means that the couples nesting in the season earlier hunted more Apodemus mice. The substitution of Apodemus mice hasnt changed (the influence on the time of nesting wasnt shown)