Fig. 3: Ecological differentiation between Western and Eastern lineages of the lesser kestrel.

a Reconstructed breeding and non-breeding ranges for Western and Eastern evolutionarily significant units (ESUs) obtained through species distribution models based on selected bioclimatic variables, largely matching the known distribution ranges of the species (Fig. 1, Supplementary Fig. 14). b (Top) Habitat use for each combination of lineage and season calculated as the proportion of seven main land cover categories (pooled from 22 original land use categories from the Copernicus Land Monitoring Service; Supplementary Table 3) in all 2.5 arc-minute grid cells with breeding or non-breeding occurrence records. (Bottom) Heatmap of habitat preference/avoidance for each of the seven main land cover categories based on a sign test of habitat selection. White cells (f ~ 0.5) indicate habitats used proportionally to their availability, red cells (f > 0.5) indicate preferred habitats and blue cells (f < 0.5) indicate avoided habitats. c–d Climatic niche comparison between Western and Eastern ESUs in a two-dimensional space defined by the first two axes of a principal component analysis (PCA) of available climatic conditions across breeding (c) and non-breeding (d) ranges of the Western (orange contour lines) and Eastern (blue contour lines) lineages. The x-axes represent a gradient of increasing coldness (warmer climates in darker red, colder climates in darker blue), whereas the y-axes represent a gradient of increasing precipitation (beige to darker blue). The solid and dashed contour lines represent 100% and 75% of the available (background) climate, respectively. Coloured areas represent climatic niches (kernel densities of the climatic conditions at occurrence records) of Western (orange) and Eastern (blue) ESUs, with darker colours denoting higher densities and transparency adjusted to facilitate the visualisation of overlaps. Schoener’s D index of niche overlap (0 = no overlap, 1 = full overlap) and the p-values of niche equivalency tests performed with the ecospat.niche.equivalency.test function from the ecospat R package (option overlap.alternative = “lower” and 1000 random permutations) are reported. Principal components 1 (PC1) and 2 (PC2) were flipped in panel d to facilitate the comparison of climatic axes shown in panel c. Data underlying all components of Fig. 3 are provided at https://doi.org/10.5281/zenodo.14988067. Background maps were obtained from the rnaturalearth v.0.3.2 R package.