Readme The two files, Fig2dataset_Dryad and Fig3dataset_Dryad, were used to generated, Fig. 2 and 3 in the paper entitled ÒThe role of a synanthropic bird in the nest niche expansion of a secondary cavity-nester to man-made structuresÓ published in Ecology and Evolution. The dataset could be opened with Excel and transferred to other formats. We analyzed the data with R v4.1.1.