Temporal variation in flight activity, foraging activity and social interactions by bats around a suburban pond
We investigated overnight and seasonal activity patterns of different bat species around a suburban pond between April and September 2003. Among the seven species identified, three (Pipistrellus pipistrellus, Pipistrellus nathusii and Myotis daubentonii) showed the highest level of occurrence and/or flight activity. Flight activity of Pipistrellus pipistrellus greatly varied over time, with the highest levels occurring just after sunset. The activity of Pipistrellus nathusii and Myotis daubentonii remained constant for at least the first few hours after sunset. Flight and foraging activities of all species changed with the reproductive period. Whereas flight activity increased from pregnancy to post-lactation in Pipistrellus, it decreased during post-lactation in Myotis daubentonii. We demonstrated an increase in social calls among Pipistrellus pipistrellus during the first hours of the night and, markedly so, during the post-lactation period. These results are discussed in relation to the species’ ecology and behaviour.