The Mode of Orientation during Flight and Approach to Landing in two Phyllostomid Bats


Zoologisches Institut der Universität, Poppelsdorfer Schloß, D-5300 Bonn 1.


The use of vision during flight and approach to a landing site in two phyllostomid bat species, Phyllostomus discolor and Desmodus rotundus was investigated. Three individuals of each species were trained to traverse a 3-m flight tunnel and to land at a small illuminated grid that was randomly changed between two positions on a front wall. Analysis of the flight path by observation and different technical methods revealed that the bats oriented themselves toward the grid quite early. When the illumination was switched off the flight path diverged much later. With a dark landing grid on one side and an optical projection of it on the other the bats aimed towards this dummy, interrupted the approach 20–40 cm in front of the illusion and then tried to reach the other side or turned back. Whether microchiroptera may rely in the medium range more on vision than usually is thought is discussed.