Physiological response of a wild rodent to experimental manipulations in its natural environment using infrared thermography
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Biodiversity Conservation Laboratory, Department of Environment, University of the Aegean, 81100 Mytilene, Greece
Yiannis G. Zevgolis   

Biodiversity Conservation Laboratory, Department of Environment, University of the Aegean, 81100 Mytilene, Greece
Online publication date: 2022-03-15
Publication date: 2022-03-15
Hystrix It. J. Mamm. 2022;33(1):0
Heat loss from non-insulating body parts of rodents can be used as a proxy to Stress-Induced Hyperthermia (SIH) and can be detected via non-invasive methods, such as infrared thermography (IRT). Although IRT has been systematically used to detect SIH in captive or laboratory animals, very few studies have been performed in wild situations. We investigated the SIH in a wild rodent, the Eastern Broad-toothed Field Mouse Apodemus mystacinus, faced with novel stressors in its natural habitat, using IRT. We subjected live-trapped individuals to six consecutive experimental manipulations (Experimental Manipulations Phase - EMP), and then we temporarily transferred them to a wooden box to partly overcome the stressful challenges (Transitory Release Phase - TRP). We used the maximum eye temperature difference between the start of the EMP and the start of the TRP (ΔTSIH) as the best estimate of SIH. Mean eye temperature during EMP differed significantly from that of TRP for each individual and the differences were similar when examined separately as to sex, trapping history, or breeding condition. Comparison of eye temperature time series for different trapping history groups showed a higher similarity of the response of first captures with 2nd and 3rd recaptures than of first captures with 1st recaptures, verified by a comparison of ΔTSIH for these groups. Larger-sized first-captured individuals appeared less stressed by the experimental procedure than smaller-sized individuals. Overall, IRT appears to be a useful and feasible method for non-invasive monitoring of SIH.
We are very grateful to the Editor-in-Chief Dr Lucas A. Wauters as well as to Marina Morandini for their constructive comments, suggestions, and extensive editing of our original manuscript, greatly improving it. We would also like to thank K. Vlachopoulos for valuable discussions and help with the data analysis, G.D. Kokkoris for his effective guidance in statistical methods and G. Charea for her help during field work.
This research is carried out / funded in the context of the project “Study of acute and chronic physiological and behavioral response of small mammals to stressful stimuli, using non-invasive methods in field sampling conditions” (MIS 5048921) under the call for proposals “Supporting researchers with an emphasis on new researchers” (EDULLL 103). The project is co-financed by Greece and the European Union (European Social Fund- ESF) by the Operational Programme Human Resources Development, Education and Lifelong Learning 2014--2020.