Tools of hibernation measurement and interpretation (TOHMIN) for quantifying various values from body temperature fluctuation during hibernation

Abstract Hibernation is a fascinating physiological phenomenon that dramatically reduces metabolism, resulting in a large deviation of body temperature (Tb) from the homeothermic range in mammals. Although high-resolution and long-term Tb recording in wild or laboratory animals has become possible through bio-logging, few standardized methods for analysing the details of hibernation patterns are available, making it difficult to reproduce and compare the results across different studies and species. To facilitate the analysis of Tb patterns and aid hibernation research, we developed an open-source program, tools of hibernation measurement and interpretation (TOHMIN). As a proof of concept, we analysed a Tb dataset from pilot studies on the effects of distinct diets on hibernation patterns and differences in hibernation patterns between sexes in a mammalian hibernator, the Syrian hamster (Mesocricetus auratus), and found previously undetectable fine-scale differences in hibernation patterns. In addition, we demonstrated that TOHMIN can successfully analyse hibernation patterns in the 13-lined ground squirrel (Ictidomys tridecemlineatus) and the fat-tailed dwarf lemur (Cheirogaleus medius) both maintained under captive conditions. Furthermore, our tool helped analyse torpor patterns in mice (Mus musculus) upon restricted feeding. Thus, TOHMIN facilitates studies that assess the effects of various experimental manipulations on hibernation and torpor phenotypes (hibernation is a form of torpor) in mammals.