Movement patterns, roosting sites and diet composition during the breeding season of three different forest-dwelling owl species in an area of sympatry: a case study of male home ranges

In areas of sympatry, animals face risks associated with predation pressure and competition for space and/or food from individuals within the same or different ecological guilds. In birds of prey, intraguild competitors and adversaries may adapt to coexistence through various mechanisms, such as spatial avoidance, dietary differentiation, or using distinct habitat types in the shared environment. However, studies examining multiple sympatric owl species and simultaneously investigating their home ranges, diet, and roosting sites remain exceptional. Therefore, we studied four sympatric owl species to obtain findings on spatial arrangements of their diurnal roosting home ranges, and prey and habitat selection during the breeding season. Individual males from three of the four studied species [Eurasian pygmy owl (Glaucidium passerinum), boreal owl (Aegolius funereus), and tawny owl (Strix aluco)] were radio-tracked in an area co-inhabited by an apex intraguild predator, the Eurasian eagle-owl (Bubo bubo). The diurnal roosting home range, calculated using a 95% kernel density estimation method, was 111, 117, and 7 ha for the pygmy, boreal, and tawny owl male, respectively. The diurnal roosting home ranges overlapped by 55% in the case of the boreal and pygmy owl males; in contrast, their ranges overlapped only by 2% and 4%, respectively, with that of the tawny owl male. The tawny owl male roosted at a respectful distance from the eagle-owl’s nest site in all recorded cases, while it was included within the diurnal roosting home ranges of both smaller owl species, indicating the subordinate owl species may use the presence of an apex predator to protect themselves from medium-intraguild enemies. The study results suggest that intraguild competitors/enemies may mitigate direct conflict through spatial avoidance and dietary differentiation, and such partial niche separation may help reduce food competition within the guild, promoting coexistence among species.