The impact factors for the final return time of V. sinensis
We recorded 78 final return events of V. sinensis , and all final return events occurred and ended approximately 7–79 minutes before sunrise. There were no significant differences in the final return time between 2019 and 2020 (Paired sample t test, t = 1.730, P = 0.093).
Our analyses indicated that the best model of variation in the final return time of V. sinensis used LIFR and PAPDA as the predictor variables (Table 5). However, model averaging revealed that three predictive variables (LIFR, LISR, and PAPDA) were also significantly associated with the final return time of V. sinensis (Table 6). First, differences between the final return time and sunrise time were significantly and positively associated with light intensity at sunrise (t = 4.054,P < 0.001; Fig. 3a). That is, the higher the light intensity at sunrise, the earlier the final return time of V. sinensis. Second, differences between sunrise and final return time were significantly and negatively associated with light intensity at final return (linear regression:t = −8.194, P < 0.001, Fig. 3b; curvilinear regression: t = −10.226, P < 0.001, Fig. 5c). Finally, bats also returned to the roost later when predators were present (t = −5.746, P < 0.001; Fig. 3c). We found that predators were often (60% records at dawn) present before the ending of the final return events at dawn. However, the number of successful predation events occurring at dawn was significantly less than at dusk (Mann-Whitney U test, Z = -1.993, P = 0.046). Consistent with the results of the hierarchical partitioning analysis, the independent contributions of LIFR, LISR, and PAPDA were 56.34%, 6.18%, and 37.49%, respectively (Fig. 4c).