Temporal pattern of activity of Pipistrellus pipistrellus in the Hranická Chasm

In 2008 flight activity of common pipistrelles, Pipistrellus pipistrellus was studied in the Hranicka Chasm (near Hranice na Moravě, C Moravia, Czech Republic). The research was focused on the overnight changes in activity during 17 monitored nights in aproximately fourteen days intervals from April to November. Recordings of bat calls acquired by an automatic ultrasound detection afforded the main data source. Each night was divided into eight periods (1-8) and the season of monitoring into five parts (A-E) related to the reproductive cycle of bats. Relative activity defined as the number of minutes with the record of a pipistrelle call related to an hour of recording (min+/hour) reached the peak in July and August while it was the lowest in April. The highest level of the overnight activity was recorded around the midnight during most nights. Bat activity was positively correlated with air temperature especially at the beginning and the end of the season.