HOMING ABILITY AND ORIENTATION IN PAINTED TURTLE CHRYSEMYS PICTA MARGINATA

The homing abilities of 45 painted turtles, Chrysemys picta marginata, were examined by observing their behavior when transported to release sites varying distances from their home pond. The turtles displayed a marked tendency to orient homeward when released 100 meters to the north, south, or east. This ability disappeared entirely, however, when the distance of displacement was increased to one mile. Studies of possible orientational cues used during these short homing trips indicated the following: (1) Turtles did not tend to orient by simple, positive geotaxis although such downhill movements could have partially explained the homing results. (2) Homeward orientation did not correlate with wind direction at the time of release. Consequently, olfactory cues emanating from the home pond probably are not essential guiding stimuli. (3) Turtles released under conditions of complete overcast continued to display accurate homeward orientation, thereby arguing against the importance of celestial cues. The use of a form of bicoordinate celestial navigation for homing over short distances is further dispelled by a consideration of the extraordinary sensory capabilities required by such hypotheses. (4) When turtles were blindfolded prior to their release, there was a pronounced deterioration both in homeward orientation (random) and in the straightness of the paths traversed. These results, together with analyses of the actual paths followed by individual turtles, suggest that visual recognition of local topographic landmarks may play an important role in enabling Chrysemys to return to their home ponds. The possession of such a simple, short-distance, homing ability would seem well adapted to the needs of a relatively sedentary species such as the painted turtle. © 1969, Brill. All rights reserved.