Table 2.

Component matrix with loadings of the PCA

Acoustic Variable	Principal Components
	1	2	3
Mean fo (Hz)	0.97	0.18	0.08
Minimum fo (Hz)	0.97	0.09	−0.01
Maximum fo (Hz)	0.94	0.20	0.07
End fo (Hz)	0.93	0.10	−0.01
Start fo (Hz)	0.93	0.08	−0.02
Mean amplitude (dB)	0.17	0.97	0.15
Maximum amplitude (dB)	0.19	0.96	0.13
Minimum amplitude (dB)	0.10	0.96	0.17
Jitter	−0.16	−0.08	−0.90
Tonality	−0.14	0.29	0.84
% of variance explained	51.62	27.59	12.19
Eigenvalue	5.16	2.76	1.22

The dimension of the acoustic variables measured from defensive calls (N = 377) were reduced to three PCs. Loading higher than 0.5 are highlighted in bold