Detail of the spectrogram area highlighted red in Figure 19. Two 5-second segments are shown to illustrate the length of BirdID-Europe254 classification windows in relation to common bird songs and calls. Since in practice the analysis is computed with a step size of two seconds, we have omitted the respective overlapping classification windows for the sake of simplicity. Spectrogram settings – sample rate 48 kHz, DFT size 1024 samples, grid spacing 46.9 Hz, Window Hann, overlap 50 %. The spectrogram was truncated above 14 kHz because only noise was present in the high-frequency range.