Habitat Suitability Modelling for the Krüper's Nuthatch (Sitta krueperi) in the Kaz Mountains and Surrounding Area

Biodiversity loss, habitat fragmentation and climate change are among the primary environmental pressures affecting species distributions. The fact that species dependent on specific habitat conditions are particularly sensitive to environmental changes makes the identification of potential habitats crucial from a conservation biology perspective. In this study, the potential habitat suitability and distribution patterns of the Krüper’s nuthatch (Sitta krueperi), a bird species live to the Eastern Mediterranean region, were modelled using the MaxEnt (Maximum Entropy) method in the Kaz Mountains and surrounding areas. Thirty sightings of the species obtained during field surveys, along with bioclimatic, topographic and remote sensing-based environmental variables, were incorporated into the model. The multiple relationships between environmental variables were assessed using Pearson correlation analysis, and variables showing high correlation were excluded from the analysis. In model calibration, 70% of the data was used for training and 30% for testing, with analyses conducted in 10 replicates. The model performance was found to be high, with AUC values of 0.947 and 0.927 calculated for the training and test data, respectively. Jackknife analyses indicated that the August NDVI, March NDVI, annual mean temperature (BIO1), Topographic Position Index (TPI) and Topographic Wetness Index (TWI/CTI) variables had the strongest influence on species distribution. Response curves revealed that habitat suitability increases in areas with high vegetation cover density, whilst it decreases under conditions of rising temperature and high humidity. Habitat suitability maps indicated that the most suitable areas for the species are concentrated in coniferous forest ecosystems at medium elevations. The results obtained demonstrate that the distribution of S. krueperi is largely shaped by vegetation structure, topographic features and climatic conditions, thereby providing a scientific basis for planning and management efforts aimed at the species’ conservation.