title: In-flight corrections in free-flying barn owls (Tyto alba) during sound localization tasks.
abstract: Barn owls localize a stationary auditory target with high accuracy. They might also be able to hit a target that is intermittently moving while the owl is approaching. If so, there should be a critical delay before strike initiation, up to which the owl can adapt its flight path to a new stimulus position. In this study, this critical stimulus delay was determined in a three-dimensional free-flight paradigm. Barn owls localized a pulsed broadband noise while sitting on a perch in total darkness. This initial signal stopped with the owl's take-off and an in-flight stimulus (target sound), lasting 200 ms, was introduced at variable time delays (300-1200 ms) during the approximate flight time of 1300 ms. The owls responded to the in-flight signal with a corrective head and body turn. The percentage of trials in which correction turns occurred (40-80%) depended upon the individual bird, but was independent of the stimulus delay within a range of 800 ms after take-off. Correction turns strongly decreased at delays >or=800 ms. The landing precision of the owls, defined as their distance to the in-flight speaker, did not decrease with increasing stimulus delay, but decreased if the owl failed to perform a correction turn towards that speaker. Landing precision was higher for a short (50 cm) than for a large (100 cm) distance between the initial and the new target. Thus, the ability of barn owls to adapt their flight path to a new sound target depends on the in-flight stimulus delay, as well as on the distance between initial and novel targets.
authors.affiliation: Institute of Biology II, RWTH Aachen, Kopernikusstrasse 16, 52074 Aachen, Germany. laura@bio2.rwth-aachen.de
authors.forename: Laura
authors.initials: L
authors.lastname: Hausmann
authors.forename: Dennis T T
authors.initials: DT
authors.lastname: Plachta
authors.forename: Martin
authors.initials: M
authors.lastname: Singheiser
authors.forename: Sandra
authors.initials: S
authors.lastname: Brill
authors.forename: Hermann
authors.initials: H
authors.lastname: Wagner
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D005426:Flight, Animal; D019416:Head Movements; D011930:Reaction Time; D013017:Sound Localization; D013028:Space Perception; D020305:Strigiformes / Q000502:physiology*; D014741:Video Recording