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Table 1 Advantages and disadvantages of different methods used to measure body temperature of birds and mammals

From: Challenges of measuring body temperatures of free-ranging birds and mammals

Method Capture Surgery Continuous Advantages Disadvantages
Thermometry, e.g. rectal, oesophageal × × Quick, low-cost, core temperature measurement Single point measurement, difficult to make on freely moving animals. Stress responses may influence body temperature
Implanted data loggers Measurement of internal temperature(s) over many months/years. Can be combined with other sensors, e.g. heart rate Surgical constraints, most cases require recapture for data recovery. Data logger size limitations
Radio transmitters: Implanted Measurement of internal temperature(s) that can be remotely recorded Measurement duration limited by battery power. External receiver or manual data logging system required for continuous recording
Radio transmitters: Skin surface × Remote measurement of skin temperature. Easily attached by glue As above. Skin temperature is influenced by environmental conditions as well as physiological parameters. Signal noise increased by movement. External devices increase drag
Gastrointestinal devices × Deployment by feed tube/ingested. Continuous recording of internal temperature. Detection of prey/food intake May require anaesthesia or sedation. Temperature influenced by ingestion/digestion. Measurement period may be limited by gut passage time. Device size limitations
Non-surgical implants, e.g. rectal, aural, vaginal × Internal temperature measurement avoiding surgery Temporary measurement of body region may constrain biological function and limits measurement duration
Faecal temperature × × × Non-invasive proxy of rectal temperature Calibration of rectal temperature with faecal temperature required. Temperature prone to vary with environmental conditions
PIT tags × × Low-cost, minimally invasive, multiple discrete measurements avoiding recapture. Temperature measurement possible throughout life of organism Non-continuous measurement limited by RFID receiver placement. Reading range restricts measurement to close proximity. Migration of tag in some cases
IR thermography × × Remote, non-invasive, sampling with high spatial and temporal resolution. Thermal video allows temperature measurement of discrete behaviours Influenced by environmental conditions and may not clearly reflect internal temperature. Continuous recording of thermal video over several hours may be limited by memory. Animal must be within field of view of researcher/camera
IR thermometry × × × Remote, non-invasive recording of surface temperature. Low cost (cf. IRT) Spatial resolution limited by increasing measurement area with distance. Typical distances of 1–5 m
Temperature-sensitive paint × × Rapid assessment of temperature range of surface by colour change Low accuracy and resolution. Toxicity and visual marking may affect health/behaviour/predation risk
  1. Capture, surgery or continuous recording is noted: yes (), no (×)