Weather conditions considerably influence the behavior of wildlife, particularly those living in harsh habitats such as the plateau. In this study, we reported unusual flight behavior of Black-necked Cranes (Grus nigricollis) where legs are drawn up. Among 15 crane species, it is the only species that spends its entire life in alpine areas. Field observations were conducted during the three winters of 2006/07, 2009/10, and 2012/13 at Dashanbao National Nature Reserve (DNNR), northeastern Yunnan, China. At the population level, ~4% of Black-necked Cranes displayed this behavior, whereas a total of 156 individuals from 49 flocks displayed this behavior among the clearly observed 4,007 individuals of 751 crane flocks. Our results showed a strong negative correlation between prevalence of this behavior and departure temperature (r = −0.832, P = 0.005, n = 9). Moreover, the average temperature of the preceding 12 hrs and duration of exposure to subzero temperature had a significant effect on the occurrence of leg-drawn-up flight behavior (P < 0.05), whereas the extreme low temperature of the preceding 12 hrs did not significantly affect the prevalence of this behavior (F1,3 = 1.974, P = 0.26). We inferred that this infrequent flight posture developed as a behavioral response to the low air temperature and duration of exposure.