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Význam dravců (Accipitriformes, Falconiformes) a sov (Strigiformes) v agrocenózách a antropogenní faktory, které je ovlivňují.
Seligová, Renáta
The aim of the thesis is to assess the effect of biological protection and anthropogenic effects that influence the number of raptors and owls in agrocenoses. The importance of these predators as biological protection of crop-plants against rodents is on the rise in the past decades. There is also an effort to examine the relationship between raptors and their prey to understand the topic better. From 2015 to 2017, 8,693 mouse-eating raptors and owls have been accepted to animal rescues in the Czech Republic. Although, it is necessary to take into account that only about 1% of injured birds get to the rescues. Most of them die further from the place of injury or become a prey of other predators. The majority of birds had been accepted due to injury, mostly because of electric wire burns (30.63%), road hit (21.85%) or obstruction impact (9.33%). Injury by another animal, feather damage and gun wound were not a rarity either. 42.95% of accepted birds died – 18.49% of these had to be destroyed (especially if the cause of injury was electric burns or road hit). The extent of anthropogenic threat on raptors and owls was analysed based on the abovementioned data. The last part of the thesis deals with the effect of biological protection against common voles (Microtus arvalis). Two specimens – Falco tinnunculus and Buteo buteo – were assessed on an area of 100 km2 with the estimated 26 pairs of each species. Several factors had to be taken into account in the estimate. The population of Falco tinnunculus removed 52,767 common voles per year and the population of Buteo buteo removed 177,708 of common voles per year. The predatory pressure on the vole is estimated to 12.9%. Even thought the number should not be omitted, it would not be accurate to state whether biological protection functions or not. There are several variables that must be taken into account. The result of the estimate is based on middle population density of common vole, thus it would much lower in case of accession of population gradation. On the contrary, raptors and owls can accelerate the fall of the population after gradation culimation and maintain a longer interval before a new gradation.
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