Julius Orlowski, Wolf Harmening, Hermann Wagner
Department of Zoology and Animal Physiology, Rheinisch-Westfaelische Technische Hochschule Aachen University, Aachen, Germany.
Journal of vision 2012Barn owls are effective nocturnal predators. We tested their visual performance at low light levels and determined visual acuity and contrast sensitivity of three barn owls by their behavior at stimulus luminances ranging from photopic to fully scotopic levels (23.5 to 1.5 × 10⁻⁶). Contrast sensitivity and visual acuity decreased only slightly from photopic to scotopic conditions. Peak grating acuity was at mesopic (4 × 10⁻² cd/m²) conditions. Barn owls retained a quarter of their maximal acuity when luminance decreased by 5.5 log units. We argue that the visual system of barn owls is designed to yield as much visual acuity under low light conditions as possible, thereby sacrificing resolution at photopic conditions.
Julius Orlowski, Wolf Harmening, Hermann Wagner. Night vision in barn owls: visual acuity and contrast sensitivity under dark adaptation. Journal of vision. 2012;12(13):4
PMID: 23220576
View Full Text