Sound localization acuity and its relation to vision in large and small fruit-eating bats: II. Non-echolocating species, Eidolon helvum and Cynopterus brachyotis.
Passive sound-localization acuity for 100-msec noise bursts was determined behaviorally for two species of non-echolocating bats: the Straw-colored fruit bat, Eidolon helvum, a large frugivore, and the Dog-faced fruit bat, Cynopterus brachyotis, a small frugivore. The mean minimum audible angle for two E. helvum was 11.7 degrees, and for two C. brachyotis was 10.5 degrees. This places their passive sound-localization acuity near the middle of the range for echolocating bats as well as the middle of the range for other mammals. Sound-localization acuity varies widely among mammals, and the best predictor of this auditory function remains the width of the field of best vision (r=.89, p<.0001). Among echolocating and non-echolocating bats, as well as among other mammals, the use of hearing to direct the eyes to the source of a sound still appears to serve as an important selective factor for sound localization. Absolute visual acuity and the magnitude of the binaural locus cues available to a species remain unreliable predictors of sound-localization acuity.
Department of Psychology, University of Toledo, Toledo, OH 43606, United States. Rickye.Heffner@utoledo.edu
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D000161:Acoustic Stimulation; D000818:Animals; D001309:Auditory Threshold; D049628:Body Size; D002685:Chiroptera / Q000502:physiology*; D003463:Cues; D004455:Echolocation; D005260:Female; D008297:Male; D012160:Retina / Q000166:cytology / Q000502:physiology; D013017:Sound Localization; D014792:Visual Acuity; D014794:Visual Fields