The function of a migration corridor for a passerine: A case study based on age and gender of blue-and-white flycatcher (cyanoptila cyanomelana)

Abstract

Birds of different ages or sexes may select different migration strategies. We studied the spring and autumn migration as well as the body condition of different ages and sexes of the Blue-and-white Flycatcher Cyanoptila cyanomelana at a migration corridor in Yancheng, Jiangsu, China, in 2017. A total of 121 individuals were captured in mist nets, 62 in spring and 59 in autumn. We found that adult males were caught significantly earlier than females in both seasons (Mann-Whitney U test, spring, P = 0.012; autumn, P=0.019), but the migration timing of immature birds was much the same as adults of the same sex in both seasons (Mann-Whitney U test, spring, P=0.571; autumn, P=0.236). Body size and sex were found to affect body mass significantly (ANCOVA, wing length P =0.001; sex P=0.001). No individuals were recaptured in both migration seasons, hence the Blue-and-white Flycatcher may adopt a strategy of one-day stopovers. The Yancheng seawall forest may represent a low-quality habitat for this species, and birds pass this location quickly in search of other suitable habitats.