The raw data on daily activity timing of bats and R codes

The timing of daily activity constitutes animals’ temporal niche that experiences pressure from extrinsic and intrinsic factors. However, the extent to which these factors govern daily activity timing in most animal taxa remains largely unknown. Bats exploit the nocturnal niche and are sensitive to nighttime environmental changes. Here, we used least horseshoe bats (<i>Rhinolophus pusillus</i>) to explore the relative contributions of light conditions, weather variables, and reproductive status to daily activity timing at the colony level. We monitored the timing of emergence, return, and duration of nocturnal activity in <i>R. pusillus</i> by recording their echolocation calls at roost entrance across reproductive and non-reproductive seasons. We measured nightly light intensity and ambient temperature at roost entrance in real-time using high-precision sensors. Additional variables relevant to bat activity were recorded, including moon phase, cloud cover, wind speed, rainfall, and reproductive state. To account for natural temporal variation, bats’ emergence time, return time, and nocturnal activity duration were standardized relative to sunset, sunrise, and night length, respectively. Our analyses revealed that light intensity, environmental temperature, and reproductive status significantly affected daily activity timing in bats after controlling for the number of bat passes. Bats delayed evening emergence and returned earlier under conditions of elevated light intensity. Bats returned later and prolonged the duration of nocturnal activity on warmer nights. During pregnancy and lactation, bats emerged earlier and returned later, extending duration of nocturnal activity. Light intensity explained the largest proportion of variation in emergence time, whereas reproductive status predominantly explained the differences in return time and activity duration.These results demonstrate that both light conditions and reproductive state are key determinants of daily activity timing in bats. This study provides new insights suggesting that light-induced environmental risks and reproductive demands exert differential effects on the emergence and return behaviors in bats.