In-flight corrections in free-flying barn owls (Tyto alba)during sound localization tasks

Abstract

SUMMARYBarn 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 freeflight paradigm. Barn owls localized a pulsed broadband noise while sitting on a perch in total darkness. This initial signal stopped with the owlʼs 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 ≥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. Supplementary material available online at

Development of auditory sensitivity in the barn owl

“…are nocturnal predators with well-developed sound localization abilities (Payne 1971; Konishi 1973; Hausmann et al 2008), and large hindbrain auditory nuclei (Kubke et al 2004). Generally, physiological studies of development in these owls have focused on the role of adaptive plasticity and instructed learning during development of sound localization circuits (Knudsen et al 1984; Gold and Knudsen 2000; Miller and Knudsen 2001; Miller and Knudsen 2003; see reviews in Pena and DeBello 2010 and Knudsen 2002).…”

Leap and Strike kinetics of an acoustically 'hunting' barn owl Tyto alba

“…1A) (Cramp, 1985), and are capable hunters, predominantly of mice, voles and shrews [summarized in Cramp (Cramp, 1985)]. Hunting can be targeted entirely acoustically, enabling effective location of prey even when hidden under leaves and in complete darkness (Payne, 1971; Hausmann et al, 2008). What role might the long legs play in hunting?…”

Coding space-time stimulus dynamics in auditory brain maps

“…In the ICx and OT maps of barn owls, locations in the front and below eye levels are over-represented (Figure 4A; Knudsen and Konishi, 1978a; Knudsen, 1982). This mapping may reflect orienting behavior, as owls face the target during pursuit (Payne, 1971; Hausmann et al, 2008) and descend from a height to capture prey (Volman, 1994). Distortions on the sensory surface are also consistent with the notion that space maps may represent a “place-coded probability distribution” (Knudsen et al, 1987; Fischer and Peña, 2011).…”