A five-year (2018 – 2022) study of the Eagle Owl Bubo bubo in Croatia. The recolonisation and number estimates of the Eagle Owl in lowland Croatia

The Eagle Owl Bubo bubo is one of the largest owl species in Europe and Asia.It mainly inhabits rocky areas with suitable cliffs, where it nests.The global population trend is declining.In Croatia, the largest part of the population breeds in the Mediterranean part.The population in the lowland part was extinct in the first half of the 20 th century, but recently they have been observed breeding again.The aim of this paper was to present the results of a five-year study of the Eagle Owl in three parts of Croatia: the lowland, the Primorje and Gorski kotar; and Istria.From 2018 to 2022, educated volunteers collected data about the Eagle Owl active territories by listening to spontaneous singing from 1 st February until 15 th March.A total of 485 visits were made to 154 locations, and 60 active territories of the Eagle Owl were found.The estimated size of the breeding populations in the lowland part is 32 to 45 active territories, while for Primorje and Gorski kotar, as well as Istria, further research ought to be conducted in order to estimate the population size.