Figure 1

Sampling localities of common nightingales (red) and thrush nightingales (blue) in Poland and the Czech Republic. The distribution areas of common and thrush nightingale are in red and blue, respectively. The sympatric area, where both species co-occur, is in violet. The map was generated using QGIS v.3.10 (http://qgis.osgeo.org) with species ranges distribution from BirdLife International67,68 and modified following Reif et al.60.