Bioclimatic Preferences of the Great Bustard in a Steppe Region

(1) The intercorrelated effects of climatic processes and anthropogenic land use changes have been shown to govern the population declines in several bird species, which have led to global extinctions. Ground-nesting birds are especially sensitive to modifications in spatial as well as temporal patterns of climatic change. The Great Bustard (Otis tarda) is one of the most endangered species, which has suffered considerable range contractions and population declines in extensive areas of its historical distribution. (2) Here, we aim to (i) identify the key climatic predictors governing the historical distribution of the Great Bustard within the Carpathian Basin during the past three decades, (ii) provide spatial predictions for the historical range of the study species, and (iii) identify areas where species-specific conservation planning initiatives need to focus on by predicting the distribution of the Great Bustard for future time periods. To do so, here we apply bioclimatic niche modeling implemented in the MaxEnt software package, which is fitted on historical occurrence locations as a function of potential bioclimatic predictors. (3) We show that (i) the most important bioclimatic predictors governing the distribution of the Great Bustard are the annual mean temperature, mean temperatures of the wettest and driest quarters, as well as the annual precipitation; (ii) all lowland areas of the Carpathian Basin were suitable for the Great Bustard during historical time periods; (iii) the SDM predictions show the historical suitability of the Muntenia and Dobrodgea regions and the Upper Thracian Plain; and (iv) the future projections show a substantial decrease in the core distribution area, whereas the boundary areas are expected to remain stable. In summary, our study emphasizes that the distribution modeling of endangered taxa using historical records can strongly support species-specific conservation planning initiatives.