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Fig. 2 | Frontiers in Zoology

Fig. 2

From: Neuroendocrine patterns underlying seasonal song and year-round territoriality in male black redstarts

Fig. 2

Male black redstarts’ song spectrogram and analysis. A whole strophe (a) of a male black redstart song (Spectrogram: R package “seewave” [51], sample rate 22, 050 Hz, FFT = 512 points, Hanning-Window, overlap: 70%), illustrating the structural components of the song: Part A, Part B and Part C. The syllable type (1-2-3-4-5) and the syllable division are shown in the upper part, for example, syllable type 1 has 5 elements. Part B is a single atonal element. Spectrogram also shows the pause between Part A and Part B and how acoustic frequencies were defined. The mean estimates ± 95% CI and data points of song rate (b), song features (c, d) and song repertoire (e, f, g) analyses across seasons are shown in the lower panels. Song rate 10-min after the STI (b) did not differ between breeding (N = 9) and nonbreeding (N = 8; p = 0.5), and both were significantly higher compared to molt (N = 8; p = 0.01, p = 0.008). The maximum frequencies of part A (c) and part B (d) were lower during breeding (N = 8) compared to nonbreeding (N = 6; p = 0.04, p = 0.05). The maximum frequency of part C (not shown) had a similar tendency but without significant difference. The number of song types (e) and the number of syllables per song (f) did not significantly differ between stages. The repertoire size (g) of part C was larger during breeding (N = 8) compared to nonbreeding (N = 7; p = 0.047) and larger than the repertoire size of part A during breeding (p = 0.01). Individual data are shown for all the panels. For the max. frequency of part A and B the individual mean of 20 strophes is shown. Asterisks indicate significance (* = p < 0.05, ** = p < 0.01)

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