Apodemus speciosus play an important ecological role in Japanese forests through their almost exclusive consumption of acorns throughout Autumn and Winter. Recent work has explored the negative effects of acorn tannins on A. speciosus, as well as the importance of tannin acclimation and physiological adaptations that help mice survive over the coldest months on a potentially toxic diet. There is growing evidence that ambient temperature may also play a role in the ability of mammalian herbivores to consume toxic diets, with some recent studies finding temperature-dependent changes in diet selection and reduced detoxification capacity in the liver at high ambient temperatures.

We fed acorns (6.2% tannin DW) to 30 wild-caught A. speciosus housed at either 20°C or 10°C. Mice kept at 10°C ate more acorns than those kept at 20°C and maintained body weight despite increased tannin intake. Ambient temperature had a significant effect on the time taken for an anesthetic (hexobarbital) to be cleared by the liver. Mice at 10°C were able to process the anesthetic more quickly than those at 20°C, indicating an increased detoxification capacity at 10°C. These results suggest that environmental temperature may play a significant role in the tolerance of wild A. speciosus to tannins.