Table 2 Summary results of principal components analysis (PCA) of external measurements of Brachypteryx montana cruralis, B. m. sinensis, and B. m. goodfellowi (individual PC I and PC II scores graphed in Fig. Y)
Component loadings | PC I | PC II | PC III |
|---|---|---|---|
External measurement | |||
Culmen from skull | − 0.27 | 0.17 | 0.16 |
Culmen from feathers | − 0.35 | 0.14 | 0.09 |
Bill width | 0.07 | − 0.01 | 0.01 |
Bill depth | − 0.07 | 0.06 | 0.04 |
Wing length | 0.69 | 1.35 | − 1.32 |
Primary projection | − 0.68 | 0.46 | − 0.38 |
Primary 1 length | − 0.66 | 0.07 | − 0.36 |
Primary 1 shortfall | 0.95 | 0.87 | − 0.68 |
Primary 2 shortfall | 0.38 | 0.82 | 0.16 |
Primary 3 shortfall | 0.02 | 0.47 | 0.29 |
Primary 4 shortfall | 0.08 | 0.19 | 0.04 |
Primary 5 shortfall | 0.01 | 0.02 | 0.00 |
Tail length | 3.39 | 0.52 | 0.62 |
Tail graduation | − 0.30 | 1.22 | 1.24 |
Undertail coverts to tail tip | 2.96 | − 0.69 | 0.09 |
Tarsus length | − 1.37 | 0.69 | 0.63 |
Tarsus distal width | − 0.13 | 0.05 | 0.01 |
Hind claw length | − 0.29 | 0.15 | 0.01 |
Eigenvalues | 24.881 | 6.52 | 4.96 |
% Total variance explained | 48.97 | 12.83 | 9.77 |