title: Assessing the reliability of thermography to infer internal body temperatures of lizards.
abstract: For many years lizard thermal ecology studies have relied on the use of contact thermometry to obtain internal body temperature (Tb) of the animals. However, with progressing technology, an interest grew in using new, less invasive methods, such as InfraRed (IR) pyrometry and thermography, to infer Tbof reptiles. Nonetheless few studies have tested the reliability of these new tools. The present study tested the use of IR cameras as a non-invasive tool to infer Tbof lizards, using three differently body-sized lacertid species (Podarcis virescens, Lacerta schreiberi and Timon lepidus). Given the occurrence of regional heterothermy, we pairwise compared thermography readings of six body parts (snout, eye, head, dorsal, hind limb, tail base) to cloacal temperature (measured by a thermometer-associated thermocouple probe) commonly employed to measure Tbin field and lab studies. The results showed moderate to strong correlations (R2=0.84-0.99) between all body parts and cloacal temperature. However, despite the readings on the tail base showed the strongest correlation in all three species, it was the eye where the absolute values and pattern of temperature change most consistently followed the cloacal measurements. Hence, we concluded that the eye would be the body location whose IR camera readings more closely approximate that of the animal's internal environment. Alternatively, other body parts can be used, provided that a careful calibration is carried out. We provide guidelines for future research using thermography to infer Tb of lizards.
authors.affiliation: CIBIO, Research Centre in Biodiversity and Genetic Resources, InBIO, Universidade do Porto, Campus Agrário de Vairão, Rua Padre Armando Quintas, Vairão 4485-661, Vila do Conde, Portugal; College of Medical, Veterinary and Life Sciences, Graham Kerr Building, University of Glasgow, Glasgow G12 8QQ, Scotland, UK.
authors.forename: Frederico M
authors.initials: FM
authors.lastname: Barroso
authors.affiliation: CIBIO, Research Centre in Biodiversity and Genetic Resources, InBIO, Universidade do Porto, Campus Agrário de Vairão, Rua Padre Armando Quintas, Vairão 4485-661, Vila do Conde, Portugal.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Carretero
authors.affiliation: Departamento de Biologia, Faculdade de Ciências da Universidade do Porto, R. Campo Alegre, s/n, 4169-007, Porto, Portugal.
authors.forename: Francisco
authors.initials: F
authors.lastname: Silva
authors.affiliation: CIBIO, Research Centre in Biodiversity and Genetic Resources, InBIO, Universidade do Porto, Campus Agrário de Vairão, Rua Padre Armando Quintas, Vairão 4485-661, Vila do Conde, Portugal; Departamento de Biologia, Faculdade de Ciências da Universidade do Porto, R. Campo Alegre, s/n, 4169-007, Porto, Portugal. Electronic address: marco.sannolo@gmail.com.
authors.forename: Marco
authors.initials: M
authors.lastname: Sannolo
mesh_terms: D000818:Animals; D049628:Body Size; D001831:Body Temperature; D002988:Cloaca / Q000502:physiology; D008116:Lizards / Q000502:physiology*; D008297:Male; D009799:Ocular Physiological Phenomena; D015203:Reproducibility of Results; D013817:Thermography / Q000379:methods*
keywords: Infrared camera; Lizard body temperature; Regional heterothermy; Thermal imaging; Thermography