RIVERA, A.R.*; RIVERA, G.; Clemson University; Clemson University: Thermoregulatory behavior in yearling turtles: Is there a preference for social basking?

Semi-aquatic turtles of the family Emydidae typically thermoregulate by aerial basking. This behavior is most frequent when the air temperature exceeds that of the water and when the amount of solar radiation reaching basking sites is optimal. While the general patterns of basking behavior in adult turtles are fairly well described, little more than brief anecdotal observations exist on the thermoregulatory habits of hatchling and juvenile turtles. Furthermore, although it is known that turtles often bask in groups, the social aspects of this behavior have largely been ignored. Do turtles bask gregariously because the number of suitable basking sites is limited or because of an innate preference to bask with other turtles? Basking behavior was studied in yearling Trachemys scripta to elicit information on the social aspects of this behavior. Choice experiments were conducted in an aquarium with a basking platform and lamp placed at each end. Turtles had a choice of basking alone or with a tethered, novel conspecific of equivalent size. During the three-hour test period, the typical pattern of events included a brief period of inactivity followed by a longer �surveying� phase, during which turtles traversed the tank at an increased rate. In most trials, turtles surveyed both platforms several times, although tending to utilize the occupied platform more often before selecting a basking site where they tended to remain for the duration of the trial. Turtles demonstrated an overwhelming preference for basking with the conspecific. There appears to be a clearly defined social element to the basking behavior exhibited by Trachemys scripta in this study, which is likely common to other emydid turtles.