The impact factors of the mid-emergence time of V. sinensis
We recorded 91 mid-emergence events of V. sinensis , only two events occurred before sunset. The difference between mid-emergence time and sunset ranged from −4 to 62 min. Here, the positive values meant mid-emergence events happened after sunset. The light intensity of mid-emergence events was approximately 0.6–400 lux (40.46±68.72). In addition, 90.11% (82/91) mid-emergence events occurred when the light intensity was below 100 lux, and 45.05% (41/91) of mid-emergence events occurred when the light intensity was below 10 lux.
Our analyses indicated that the best model of variation in mid-emergence time of V. sinensis used LIFE, LISS, LS, and PHNHM as the predictor variables (Table 3). Further, model averaging revealed that the four predictor variables were also significantly associated with the mid-emergence time of V. sinensis (Table 4). First, differences between the mid-emergence time and sunset time were significantly and negatively associated with light intensity of first emergence (linear regression: t = −6.73, P < 0.001, Fig. 2b; curvilinear regression: t = −9.974, P < 0.001, Fig. 5b). That is, the higher the light intensity of first emergence, the earlier the mid-emergence time of V. sinensis. Second, a significant and positive correlation between the mid-emergence time and light intensity at sunset was observed (t = 5.882, P< 0.001; Fig. 2a). Third, a significant difference in the mid-emergence time was detected between lactation and post-lactation (t = −2.903, P = 0.004; Fig. 2d). During the lactation period, V. sinensis departed earlier from the roost than during the post-lactation period (Fig. 2d). Specifically, the mid-emergence events started approximately −4–40 (15.435±10.051) min after sunset during the lactation period. In contrast, the mid-emergence events started about 12–62 (29.511±9.201) minutes after sunset during the post-lactation period. Finally, bats also departed from the roost earlier when predators were hunting (t = −3.713, P< 0.001; Fig. 2c). We found that predators were hunting bats during 36 mid-emergence events. Consistent with the results of the hierarchical partitioning analysis, the independent contributions of LIFE, LISS, LS, and PHNHM were 46.41%, 13.60%, 22.74% and 17.25%, respectively (Fig. 4b).