Effects of environmental conditions on the distribution and abundance of the boreal owl in the Czech Republic

Ing. Richard Ševčík

Doctoral thesis

Abstract:

Habitat loss, climate change, and the impact of other environmental factors may pose a potential risk to many species. To understand this risk, we need to monitor population distribution, abundance, and their changes. In this thesis, the combination of atlas data (Study I), nest-box monitoring (Study II), and bioacoustic monitoring (Study III) were used to better understand the factors driving the distribution and abundance of the boreal owl population in the Czech Republic. The most important findings are as follows; first, the Czech boreal owl population, compared to other owl species, prefers to inhabit the highest elevations characterized by cold conditions. Second, the abundance of two boreal owl populations that were monitored based on nest-box occupancy differed in the two habitat types, but it did not differ based on bioacoustic monitoring. Owls readily (8–15%) occupied nest boxes only on mountain plateaus characterized by young blue spruce (Picea pungens) and Norway spruce (Picea abies) stands, while they use nest boxes only rarely (0–1%) in mature Scots pine (Pinus sylvestris) forests in the lowland. Third, the frequency of sampling points in which boreal owls were recorded was higher in the year of increased prey abundance and at the beginning of the breeding season. The duration (the number of minutes per hour) of territorial vocalization of boreal owls increased in the year with a higher food supply later in the breeding season and showed two peaks during the night. The results of the presented work suggest: (1) boreal owls, compared to other species, may be most susceptible to climate changes and forest loss, (2) deployment of nest boxes and associated monitoring should be precisely considered for specific locations, (3) bioacoustic monitoring of boreal owl vocalization shows circadian and seasonal variability and changes greatly under varying food conditions, while simultaneously providing an excellent opportunity for future study. Based on the findings, experiences of my supervisor and collaborators, and a literature review, I also provide individual methodological recommendations for the placement of nest boxes for boreal owls and the monitoring of populations of this species in the Czech Republic.

Keywords

bioacoustic monitoring, nest boxes, breeding, habitat loss, birds of prey, atlas data, cavity-nesters

Jazyk práce: English

Datum vytvoření / odevzdání či podání práce: 8. 2. 2023

Obhajoba závěrečné práce

• Vedúci: doc. Ing. Markéta Zárybnická, Ph.D.
• Oponent: Jan Plesník, externi, Jan Hanel, externi

Czech University of Life Sciences Prague

Faculty of Environmental Sciences

Doctoral programme / odbor:
Ecology / Ecology