Visual acuity of the vampire bat, Desmodus rotundus, and its dependence upon light intensity.

The visual system of microchiropteran bats is usually considered of minor function, but reliable experimental studies are rare. In this paper the visual acuity of three (1 female, 2 male male) vampire bats (Desmodus rotundus) has been investigated in a two-choice training apparatus (striped patterns vs. gray patterns) for light intensities from 0.04 1x to 310 1x. There was a logarithmic dependence between light intensity and visual acuity. The lowest visual angle at 0.04 1x was 2 degrees 31', at 310 1x the minimum resolvable stripe width was 48'.