Flight and echolocation behaviour of three vespertilionid bat species while commuting on flyways.

This study compares the flight and echolocation behaviour of three vespertilionid bat species while they commute on flyways. We measured the bats' spatial position relative to vertical background contours and relative to the ground while recording their echolocation behaviour. In Myotis daubentonii, we found a significant influence of spatial context on the position and dimensions of flyways as well as on echolocation behaviour. In gap situations, flyways tended to be narrower and located closer to background structures, flight speeds were lower and the bandwidth of echolocation signals was larger than in edge situations. Differences in background structure did not affect flight and echolocation behaviour. When commuting in the same gap situation flyway positions and dimensions for M. daubentonii and Myotis brandtii were similar but differed from those of Pipistrellus pipistrellus, which were slightly higher and further out than those used by the Myotis species. In M. brandtii, flyway positions and dimensions remained constant over 3 years. We found species-dependent differences in signal structure, but pulse interval and flight speed were similar across all species. The influence of available space on the position of flyways, on flight speed and on echolocation behaviour is discussed.