Spontaneous daily torpor observed in the greater long-tailed hamster (Tsherskia triton)

Abstract

To overcome severe environmental conditions such as cold or food shortage, many small mammals utilize hibernation or daily torpor. Hamsters (subfamily Cricetinae) are a well-known group using hibernation and daily torpor. Interestingly, among hamsters, hibernators tend to have relatively larger body sizes. In contrast, species that use daily torpor have a small body size, although some hamsters still remain unknown in torpor characteristics. In this study, we attempted to induce torpor in the greater long-tailed hamster (Tscherskia triton), which has a large body size among hamsters, by exposing them to condition that mimic winter (short photoperiod 8L:16D and low temperature 5°C). We successfully observed a spontaneous decrease in body temperature, and the duration of the torpor bout did not exceed 24 hours. Therefore, it was revealed for the first time that the greater long-tailed hamster is a heterothermic mammal that utilizes spontaneous daily torpor.