Spatial structure of breeding settlements of the Snowy Owl (<i>Bubo scandiacus</i>, Strigiformes, Strigidae) in the tundra of the Taimyr Peninsula

Data on Snowy Owl breeding settlements and encounters in the tundra were analyzed for the periods of 1996–2007, 2012, 2014–2020 in the vicinities of the Medusa Bay (73°21ʹN, 80°32ʹE), northwestern Taimyr Peninsula, Siberia. Breeding Snowy Owls were detected in 1996, 1999, 2002, 2004, 2005, 2007, 2014, 2016 and 2019. The spatial distribution of nests, summarized for 9 breeding years, appear to be grouped (clustered). This means that the spatial population structure of Snowy Owls mostly consists of permanent breeding sites, or territorial cells. However, the distribution of these cells in the tundra area is uniform. The reasons for such an attraction to the same sites in the tundra that fail to differ from many others are not clear yet. The existing version of the “signal field” theory cannot account for this attraction: owls very rarely occupy previously used nest sites, definitely preferring new entire breeding places within these territorial cells. In fact the basis of so dividing the breeding area into permanent territorial cells and of choosing definite ones among them seems to indicate that birds are oriented to certain yet unknown features of the environment rather than only to the ecological characteristics of the habitat and/or to tracks from the previous bird activity. A summarized distribution of the Snowy Owl encounters of non-breeding birds was clustered, as well. The distribution of these clusters across the plain tundra (in rugged areas non-breeders occurred very rarely) appeared to be random. In different seasons, regardless of the breeding status, Snowy Owls may behave in very different ways: they may tend to pose closer to other owls or try to stay farther away; they may start breeding at very low lemming numbers or, vice versa, they do not breed in good nutritional conditions.