Measuring body temperature in animals is one method of measuring their response to changing environments. One of the methods used in the field is infrared thermography which measures the temperature on the body’s surface noninvasively, but it remains unclear whether these measurements reflect core body temperature accurately.

To evaluate this method in wild primates researchers from the University of Wisconsin-Madison, University of the Witwatersrand, University of South Africa and University of Lethbridge compared infrared body surface temperature to core body temperature in vervet monkeys (Chlorocebus pygerythrus). These two measures were then compared with the local climate at the time of measurement.

Implantable temperature loggers collected core body temperature measurements
To measure core body temperature every five minutes Star-Oddi’s DST centi-T temperature loggers were implanted in 14 adult vervet monkeys. The loggers were part of a long-term study on vervet thermophysiology. They were implanted in June 2016 and removed from the animals in June 2017.

14 infrared thermal images of the animals implanted with the loggers were collected. This data was then compared to the core body temperature data from the DST centi-T loggers as well as local climate data. Local climate data was based on black globe temperature measurements taken every minute.

Surface temperature connected to local climate
The data collected showed that while there was a positive association between surface temperature and core body temperature, this was connected to the local climate. Surface temperature was therefore connected to the climate at the time of measurement and not actually reflective of core body temperature.

The research group concluded that while measuring surface body temperature is an attractive method in wild primates due to its non-invasiveness, it cannot be used to approximate core body temperatures.

The paper was published in The American Journal of Primatology and can be accessed here.

Photo: Thomas Shahan