Distribution, abundance, and breeding of the imperial eagle (Aquila heliaca) in Western Slovakia in 1977–2022

The distribution, abundance, breeding success, and habitats of the imperial eagle in the mountains and adjacent lowlands of Western Slovakia were studied over the last 45 years (1977–2022), with a total of 65 breeding pairs documented. Of the 589 breeding attempts (range 2–42 per year) that were recorded, 420 were successful (74%) and produced 718 chicks altogether. Breeding success varied considerably across the years, with an average of 1.2 chicks per initiated and 1.7 chicks per successful breeding attempt. Three chicks fledged from 10.7% of the successful breeding attempts, two chicks from 50.2%, and one chick from 39.1% of them. Breeding numbers increased slowly between 1977 and 1997, with a marked increase after 1998. In two of the most recent years, 2020 and 2021, breeding numbers more than doubled. Since 2000, we have observed changes in breeding habitat preferences, where the population has shown more preference for lowland regions than mountains. Natural factors are probably driving the upward population trend, but there has also been action taken with several management measures. The conservation measures involved and their impact on population and range trends are analysed and discussed here.