Ecological Factors and their Impact on a Diet of the Long -eared Owl (Asio otus)

My thesis deals with ecology and diet of the Long - eared Owl (Asio otus). The study area a wintering place is situated near the town of Kladno. 1) The hypothesis that a high snow cover has an influence on the Long-eared Owl diet has been confirmed. 3) The thesis deals with the determination methods of small vertebrate species in Long - eared Owl's diet. The work deals with postcranial skelet as well. There was compilled the method of the sex determination in Common vole (Microtus arvalis). The sex determination was based on the morphological differences of the pelvic bones. The results (sex ratio) had been statistically tested and as such found significant. 2) There were also analyzed the skeletal remnants of the pelvic bones in the pellets. The study of the pelvic bones was carry out in order to find expected seasonal changes in the sex ratio in a dominant prey Common vole (Microtus arvalis). That hypothesis was not confirmed. Keywords: Long-eared owl (Asio otus), diet, postcranial skeleton, pelvic bone