The dataset contains the acoustic measurements of syllables from 20 collared flycatchers (Ficedula albicollis) and the diversity indices for all individuals calculated on the min-max standardized values of the duration, mean frequency and frequency band of the syllables. Syllables from 20 songs were included from each individual. For the detailed data handling, see the methods in the related paper. db_syllable_measurements.csv file contains the measurements of the syllables from 20 individual, where the columns are: -recID -> individual ID -dur -> duration of the syllable -fmean -> mean frequency of the syllable -fmin -> minimum frequency of the syllable -fmax -> maximum frequency of the syllable -fband -> frequency band of the syllable (fmax-fmin) db_diversity_indices.csv file contains the diversity indices for the 20 individual for which we provided the acoustic measurement, where the columns are: -recID -> individual ID -FRic -> Functional Richness -FEve -> Functional Evenness -FDiv -> Functional Divergence We used the modified R script of multidimFD.R by Sebastien Villeger to calculate these diversity indices. The original script is available at http://villeger.sebastien.free.fr/Rscripts.html. The modified script included in this data package doesn't standardize the FRic between individuals with the highest value.