Animal home ranges typically characterized by their size, shape and a given time interval can be affected by many different biotic and abiotic factors. However, despite the fact that many studies have addressed home ranges, our knowledge of the factors influencing the size of area occupied by different animals is, in many cases, still quite poor, especially among raptors. Using radio-telemetry (VHF; 2.1 g tail-mounted tags) we studied movements of 20 Tengmalm’s owl (Aegolius funereus) males during the breeding season in a mountain area of Central Europe (the Czech Republic, the Ore Mountains: 50° 40’ N, 13° 35’ E) between years 2006–2010, determined their average hunting home range size and explored what factors affected the size of home range utilised. The mean breeding home range size calculated according to 95% fixed kernel density estimator was 190.7 ± 65.7 ha (± SD) with a median value of 187.1 ha. Home range size was affected by prey abundance, presence or absence of polygyny, the number of fledglings, and weather conditions. Home range size increased with decreasing prey abundance. Polygynously mated males had overall larger home range than those mated monogamously, and individuals with more fledged young possessed larger home range compared to those with fewer raised fledglings. Finally, we found that home ranges recorded during harsh weather (nights with strong wind speed and/or heavy rain) were smaller in size than those registered during better weather. Overall, the results provide novel insights into what factors may influence home range size and emphasize the prey abundance as a key factor for breeding dynamics in Tengmalm’s owl.

Abstract In the last decades, large carnivores – the grey wolf (Canis lupus), Eurasian lynx (Lynx lynx) and brown bear (Ursus arctos), and to a certain extent also the wildcat (Felis silvestris) – have increased their distribution ranges throughout Europe. Monitoring of their current distribution and population trends in the Czech Republic is crucial for the effective conservation and elimination of possible conflicts with humans in the future. In the last years, many projects focused on small-scale monitoring of large carnivores were implemented in the Czech Republic and the neighbouring mountain ranges of Slovakia. Using their results, we compiled the dataset from different regions and analysed the recent distribution of large carnivores and the wildcat. The distribution maps are based on verified data on the presence and reproduction in 2012–2016. This is consistent with the standardized methodology used across Europe. The Eurasian lynx was the most widespread of all large carnivore species in the Czech Republic, with the two trans-boundary populations (Carpathian and Bohemian-Bavarian-Austrian) occupying 94 out of 868 squares (10.8%) of the mapping grid of the Czech Republic. Reproduction was confirmed in 46.8% of the occupied squares. The grey wolf occupied 6.8% of the squares in the Czech Republic and its reproduction was confirmed in 10.2% of the occupied squares. Three reproducing packs belonging to the Central European lowland population were confirmed and the area occupied by the species increased three times within the study period. The brown bear occupied 2.8% of the squares of the Czech Republic – the area is restricted to the Carpathians – with no signs of reproduction; its distribution fluctuated heavily during the study period. The wildcat occupied the smallest range of the Czech Republic among the studied species (1.4% of the squares) but its reproduction was confirmed in a trans-boundary area (White Carpathians) at the Slovakian side of the border. The wildcat also significantly increased its range from one to six squares during the study period.

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