Fig. 3
Examples of calls from the 12 species not producing FD calls consistently (the last two, underlined species are from the Paridae clade). The notes presented here in these calls are candidate F notes, at least in the sense that they seem to be much more similar to the F notes than to the D notes from the FD calls of species that do produce FD calls consistently. Spectrogram parameters: window size of 256 samples, overlap of 128 samples, FFT length of 256 points, power scaling factor of 0.6.
