Owls require 24° of motion but only 3° for static localization

Evidence

The angular range covered by the noise sweeps in our experiments exerted the strongest effect on the owl’s sensitivity. To solve the task, the angular range had to be at least 24°. The angular range necessary for motion direction discrimination was much larger than the mean error for locating points in azimuth as indicated by the head orienting response towards the sound source elicited by broadband noise bursts (Knudsen et al. 1979 ) or by the owl’s minimum audible angle (Bala et al. 2007 ). Using a pupillary dilation response, Bala et al. ( 2007 ) measured a minimum audible angle of 3° in azimuth. — Dijk, Pim van, Physiology, Psychoacoustics and…, 3181

Categorization

• QUESTION: Eightfold gap between static localization acuity (3°) and required motion range (24°) invites further mechanistic inquiry.
• XREF: connects to: Hiding motionlessly within a landscape yields encounters impossible to any active approach — Aldo Leopold, A Sand County Almanac: With Other…, 567