4 | Discussion
How small passerine birds adapt to winter is an important topic in animal ecology and physiology. Our results provided the first detailed group composition of orange-flanked bush-robins wintering in southwest China and found that the number of 2yr+ adult males in bright-blue plumages was significantly lower than the number of males in olive-brown plumages. However, the sex-ratio was only slightly skewed to males among robins with olive-brown plumages, suggesting the existence of habitat sexual segregation. Additionally, our results revealed the factors that may be influencing the daily body condition of each robin. Individual robins can fine-tune their fat reserve in response to changes in weather or food abundance. Interestingly, capturing birds may have a significant positive effect on the birds’ fat reserve, in which a capture event cuses the birds to store more fat.