Northern bats, Eptesicus nilssonii, use vision but not flutter-detection when searching for prey in clutter

(Uploaded by Plazi for the Bat Literature Project) We investigated the detection cues used by the aerial‐hawking bat Eptesicus nilssonii foraging in a cluttered environment. The bats can detect and attack rapidly moving targets within the clutter, i.e. below grass panicles, by using prey motion as a cue. Stationary objects are attacked only above the grass, but still within the clutter overlap zone. To test if the bats were guided by flutter from moth wings or by vision when searching for stationary targets, they were presented with male ghost swifts mounted on top of steel wires. There was no difference in attack frequency on live, fluttering moths compared to dead and spread ones. However, when comparing white and dark moths, we found a significantly higher attack frequency on white ones. As the attacks always were guided by echolocation calls, we hypothesize that northern bats, at least in the initial search phase, use visual cues as a complement to detect stationary ghost swifts.