Target-approaching behavior of barn owls (Tyto alba): influence of sound frequency.
We studied the influence of frequency on sound localization in free-flying barn owls by quantifying aspects of their target-approaching behavior to a distant sound source during ongoing auditory stimulation. In the baseline condition with a stimulus covering most of the owls hearing range (1-10 kHz), all owls landed within a radius of 20 cm from the loudspeaker in more than 80% of the cases and localization along the azimuth was more accurate than localization in elevation. When the stimulus contained only high frequencies (>5 kHz) no changes in striking behavior were observed. But when only frequencies from 1 to 5 kHz were presented, localization accuracy and precision decreased. In a second step we tested whether a further border exists at 2.5 kHz as suggested by optimality models. When we compared striking behavior for a stimulus having energy from 2.5 to 5 kHz with a stimulus having energy between 1 and 2.5 kHz, no consistent differences in striking behavior were observed. It was further found that pre-takeoff latency was longer for the latter stimulus than for baseline and that center frequency was a better predictor for landing precision than stimulus bandwidth. These data fit well with what is known from head-turning studies and from neurophysiology.
Institute for Biology II, RWTH Aachen University, Mies-van-der-Rohe Str. 15, 52056, Aachen, Germany. martin@bio2.rwth-aachen.de
Martin
M
Singheiser
Dennis T T
DT
Plachta
Sandra
S
Brill
Peter
P
Bremen
Robert F
RF
van der Willigen
Hermann
H
Wagner
D000161:Acoustic Stimulation / Q000379:methods; D000162:Acoustics; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D003216:Conditioning, Operant / Q000502:physiology*; D005260:Female; D005426:Flight, Animal / Q000502:physiology*; D008297:Male; D009949:Orientation / Q000502:physiology; D011235:Predatory Behavior / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D012054:Reinforcement, Psychology; D013017:Sound Localization / Q000502:physiology*; D020305:Strigiformes / Q000502:physiology*