Infrared thermography cannot be used to approximate core body temperature in wild primates

• Published in: American journal of primatology Vol. 82; no. 12; pp. e23204 - n/a
• Main Authors: McFarland, Richard, Barrett, Louise, Fuller, Andrea, Hetem, Robyn S., Porter, Warren P., Young, Christopher, Henzi, S. Peter
• Format: Journal Article
• Language: English
• Published: United States Wiley Subscription Services, Inc 01.12.2020
• Subjects: Animals; Body Temperature; Changing environments; Chlorocebus aethiops - physiology; Climate; Climate effects; Climate prediction; Infrared imaging; Infrared Rays; infrared thermography; Monkeys; Monkeys & apes; Physiological processes; Physiology - methods; Primates; Surface temperature; thermal camera; Thermal environments; Thermography; Thermography - methods; Thermography - veterinary; Thermoregulation; Uncertainty; vervet monkeys; Zoology - methods; infrared thermography; body temperature; thermal camera; thermoregulation; vervet monkeys
• ISSN: 0275-2565; 1098-2345
• DOI: 10.1002/ajp.23204

Understanding the physiological processes that underpin primate performance is key if we are to assess how a primate might respond when navigating new and changing environments. Given the connection between a mammal's ability to thermoregulate and the changing demands of its thermal environment, increasing attention is being devoted to the study of thermoregulatory processes as a means to assess primate performance. Infrared thermography can be used to record the body surface temperatures of free‐ranging animals. However, some uncertainty remains as to how these measurements can be used to approximate core body temperature. Here, we use data collected from wild vervet monkeys (Chlorocebus pygerythrus) to examine the relationship between infrared body surface temperature, core body (intra‐abdominal) temperature, and local climate, to determine to what extent surface temperatures reflect core body temperature. While we report a positive association between surface and core body temperature—a finding that has previously been used to justify the use of surface temperature measurements as a proxy for core temperature regulation—when we controlled for the effect of the local climate in our analyses, this relationship was no longer observed. That is, body surface temperatures were solely predicted by local climate, and not core body temperatures, suggesting that surface temperatures tell us more about the environment a primate is in, and less about the thermal status of its body core in that environment. Despite the advantages of a noninvasive means to detect and record animal temperatures, infrared thermography alone cannot be used to approximate core body temperature in wild primates. The difference between vervet monkey core body and dorsal surface temperatures. Temperature differences in excess of 15°C were common and occasionally exceeded 20°C at low temperatures. Research Highlights Body surface temperatures do not approximate core body temperatures. Body surface temperatures tell us more about the local climate a primate is in.