Table 3 Principal component analysis of song variables of Brachypteryx montana cruralis, B. m. sinensis, and B. m. goodfellowi
PCA1 | PCA2 | PCA3 | PCA4 | |
|---|---|---|---|---|
Duration of strophe (s) | 0.879 | − 0.003 | 0.348 | 0.192 |
Number of elements in strophe | 0.880 | − 0.176 | 0.357 | 0.100 |
Number of distinct elements in strophe | 0.898 | − 0.069 | 0.332 | 0.109 |
Rate | − 0.003 | − 0.852 | 0.093 | − 0.272 |
Maximum frequency of strophe (Hz) | 0.828 | 0.337 | 0.348 | 0.039 |
Minimum frequency of strophe (Hz) | − 0.706 | 0.525 | 0.284 | − 0.197 |
Mean frequency (Hz) | 0.467 | 0.630 | 0.510 | − 0.066 |
Bandwidth (Hz) | 0.947 | 0.048 | 0.157 | 0.113 |
Peak frequency of strophe (Hz) | 0.327 | − 0.106 | 0.681 | 0.353 |
Maximum element duration (s) | 0.438 | 0.087 | 0.013 | 0.850 |
Minimum element duration (s) | − 0.311 | 0.759 | − 0.367 | − 0.025 |
Maximum element bandwidth (Hz) | 0.901 | 0.012 | − 0.038 | 0.153 |
Minimum element bandwidth (Hz) | − 0.337 | − 0.069 | − 0.725 | 0.289 |
Duration of first element (s) | 0.044 | 0.051 | 0.002 | 0.931 |
Duration of last element (s) | 0.438 | 0.614 | − 0.107 | 0.338 |
Peak frequency of first element (Hz) | 0.753 | − 0.131 | 0.387 | 0.151 |
Peak frequency of last element (Hz) | − 0.136 | 0.777 | 0.283 | − 0.189 |
Eigenvalue | 6.751 | 3.15 | 2.22 | 2.185 |
% Variance explained | 39.713 | 18.529 | 13.061 | 12.852 |