A Categorization of Mexican Free-Tailed Bat (Tadarida brasiliensis) Chirps ýýýýý

Male Mexican Free-tailed Bats (Tadarida brasiliensis) attract mates and defend territory using multi-phrase songs that have a structured set of rules. A subjective view of their spectrograms shows similarity and dissimilarity between the chirps (a syllable within the song) of different males. We developed a rigorous algorithm to characterize the shapes of these chirps. The discrete Fourier transform allowed us to focus on frequency information while a four level Daubechies 2 wavelet decomposition allowed us to focus on time. For comparison, we compressed large data vectors into a single data point using multidimensional scaling. Segmenting chirps, to further emphasize ranges of time and frequency, gave categorizations that most closely resemble the subjective groupings.