The effect of environmental variables on owl distribution in Central Europe: A case study from the Czech Republic

Species distributional data from atlas projects collected by volunteers and professionals play an essential role in ecology and biodiversity conservation. Atlas data primarily allow evaluating longitudinal and latitudinal gradients in species distribution. However, the effects of additional factors such as elevation and associated climatic conditions and landscape structure are rarely assessed. We used the original data from the Atlas of birds breeding in the Czech Republic in terms of the presence and absence (0/1) of breeding occurrence of seven owl species in 604 mapping quadrates (each quadrate 12.0 x 11.1 km in size) to assess the effect of elevation (reaching from 100 to 1100 m a.s.l.) and temperature on the distributional patterns of the owls. Using a multivariate spatial analysis with latitude and longitude as space predictors and landscape structure as covariates, we found that elevation and temperature significantly affected owl distribution; the model explained 94.8% of the variability (p = 0.002). Only the boreal owl (Aegolius funereus) showed a clear preference for the highest elevation, and simultaneously, boreal and pygmy (Glaucidium passerinum) owls preferred the coldest environments. Eagle owl (Bubo bubo) and tawny owl (Strix aluco) most often occupied low and middle elevation of moderate temperatures. Barn owl (Tyto alba) and long-eared owl (Asio otus) inhabited the warmest areas in low elevations. Finally, little owl (Athene noctua) most often occurred in the lowest elevations of intermediate temperatures. We have documented that the elevation and associated climate conditions can work as an effective predictor to assess distributional preferences of owl species based on atlas data. The findings can be helpful when the management of owls' habitats is considered and implemented. For example, the results of our case study suggest that the boreal owl can be susceptible to global warming and intensive logging at high elevations.