Setting up the information booth and lighting
The southern bridgehead of this one century old bridge is the largest known winter site for Nyctalus noctula in northern Europe. Every year in August, several dozend N.n. meet here every night and fly through the large air vents into the bridgeheads and out again repeatedly. This has lead to an annual bat night which is celebrated at the foot of this bridgehead. (Interestingly, the northern bridgehead is not used by bats)
This peculiar behaviour in August was discovered only a few years ago and as yet there had been theories that Swedish bats might overwinter here. New discoveries by Florian Gloza using genetic analysis have shown that this is unlikely as most N.n. seem to be living in the vicinity.
2000: The public has arrived and so, hopefully, will the bats...
2000 was a year with few bats displaying August aggregation at the bridgehead. This may be due to intensive renovation work on the bridge which continued during the nights on a tight schedule and included intensive lighting and noise (railroad renovation including arc-welding). Some bats appeared anyway and were visible as well as audible with the bat detectors. Around 300-400 people from Kiel attended.
2001: Lights and information booth are set up again.
2001 the start of the show was set at 11:00 p.m. to ensure that all visitors would be able to hear and see bats without having to wait. As the renovation work had been completed earlier, there were no disturbances for the bats and they were more frequent.
One bat being shown up close.
An interesting link: on his page Karl Kugelschafter of the University of Giessen reports his discoveries concerning this bridgehead (in German).