3.1 | The composition and morphological comparison of wintering robins
In total, 94 capture events were recorded, including 61 ringed individuals and 33 recapture events. The wintering group was composed of 41% females (n = 20) and 59% males (n = 29). The number of 3yr+ males with definitive blue plumage and 2yr male with intermediate blue plumage was 2% (n = 1). Among olive-brown plumaged individuals (n =47), the sex-ratio was slightly skewed to males with 27 female-like males and 20 females (Figure. 1).
The comparison of morphological traits between females and female-like males showed that only S2 (p-value < 0.01) and P3 (p-value < 0.05) in female-like males were significantly larger than in females, while other traits, including body length, bill length, bill crack length, tarsus length, tail length and wing length, had no significant difference (Table 1).