Temperature preferences and electrocardiography of Elaphe obsoleta (serpentes)

1. Telemetered electrocardiograms and body temperatures of unrestrained rat snakes, Elaphe obsoleta, were recorded at ambient temperatures selected by the snakes in an environmental chamber. 2. Body temperatures were consistent with those previously reported for free-living Elaphe. 3. Heart rates and electrocardiographic intervals were generally equivalent to those previously reported for snakes at similar temperatures. 4. The P-R and R-T intervals generally comprised less than 30 and 60%, respectively, of the cardiac cycle. 5. The heart rate-body temperature relationship exhibited by unrestrained Elaphe over a broad temperature range suggests that it is not so uniform as has been previously reported.