Monitoring heart rate and body temperature in red foxes (Vulpes vulpes)

Abstract

Twenty-four captive-raised red foxes were surgically implanted with radios that transmitted both heart rate and body temperature. Successive fox pairs were placed in a 4.1-ha observation pen for 2 weeks and behavior was video recorded. The radio signal was recorded on the audio portion of the video tape for computer decoding. Heart rate and body temperature were measured for six behavior categories: sleeping, awake, hunting, feeding, running, and being chased. The heart rate for each of these categories was significantly different from any other (P = 0.0001). All body temperature categories were different from each other except for running and being chased (P = 0.0001). Both heart rate and body temperature increased with level of activity. The only significant difference in heart rate and body temperature between sexes was for the sleeping heart rate category, where females had higher values than males (P = 0.04). There was also a significant time of day effect showing that body temperature while awake was highest at night (P = 0.0005). Sleeping foxes displayed a pronounced sinus arrhythmia which disappeared when they became active.