9th International Deer Biology Congress

AUTHORS: Eryn M. Watson, Bradley S. Cohen, David A. Osborn – Warnell School of Forestry and Natural Resources, University of Georgia; Michele Barletta, Department of Large Animal Medicine, University of Georgia College of Veterinary Medicine; Krista B. Mitchell, Kathern E. Myrna, Taylor M. Treen – Department of Small Animal Medicine and Surgery, University of Georgia College of Veterinary Medicine; Karl V. Miller, Warnell School of Forestry and Natural Resources, University of Georgia

ABSTRACT: Temporal resolution is the rate at which the visual system of an organism can acquire and process visual information. High temporal resolution allows animals to process movement at an efficient rate, enhancing their ability to quickly negotiate complex environments as well as avoid fast moving predators [1, 2, 3]. Although the central nervous system can process large quantities of visual information, animals’ finite amount of cognitive ability within the brain means cognitive function for another sensory system must be reduced. Thus, the resolution at which temporal information is perceived varies greatly across animal taxa [4, 5]. Aspects of white-tailed deer (Odocoileus virginianus) visual perception have been previously studied. However, temporal resolution has not been measured in any wild cervid to date. Understanding the temporal resolution of deer provides insight into how visual processing and deer’s ability to react to their visual environment influences their behavior and ecology.

Critical flicker fusion frequency (CFF), the frequency at which a flashing light source is perceived as constant, is one measure of the rate at which temporal information is processed by an animal’s visual system. High CFF means the perception of a moving object is less likely to be blurred, and determination of its nature, direction, and velocity is facilitated [3, 6]. We used ERG methods to assess CFF for dark- and light-adapted vision in deer. Average CFF for 7 deer ranged from 41.0 - 77.5 Hz for rod function. Mixed rod-cone function CFF values ranged from 56.0 - 77.5 Hz for dark-adapted vision and 98.9 - 106.7 Hz for light-adapted vision. Cone function CFF ranged from 98.1 - 106.8 Hz. Our results provide a comparative context between human and deer vision, and suggest that white-tailed deer have high temporal resolution and are adapted to low-light conditions for enhanced movement detection, particularly at dawn and dusk.