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Update:November 27, 2019

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Consumption and digestion of acorns are more efficient at ambient (cold) temperature


Article title

Cold temperature improves tannin tolerance in a granivorous rodent

Author (affiliation)

Hannah R. Windley (a), Takuya Shimada (a)

(a) Department of Wildlife Biology, FFPRI, Tsukuba, Ibaraki, Japan.

Publication Journal

Journal of Animal Ecology, 2019;00:1–11, British Ecological Society, October 2019 DOI:10.1111/1365-2656.13119( External link )

Content introduction

With the increase in global warming, it is critical from the perspective of biodiversity conservation and wild-animal management to determine how changes in temperature affect the feeding efficiency and feeding behavior of wild animals.

In this study, we focused on the large Japanese wood mouse (Apodemus speciosus), which is widely distributed in Japanese forests. Our study revealed that their capability to detoxify tannins (**), a plant defense chemical (*), improves at low temperatures.

Various chemical compounds, including tannins, are primarily detoxified in the liver after being absorbed in the body. It is known that the liver’s ability to detoxify alcohol decreases at higher temperatures. Nevertheless, it remains unclear how temperature affects detoxification of tannins, one of the most common toxins found in nature.

To address this question, we fed oak acorns containing high concentrations of tannins to large Japanese wood mice maintained at either 10°C or 20°C. Next, we compared the levels of detoxification in their liver, food intake, and digestibility. Consequently, we found that the mice maintained at 10°C detoxified tannins faster and, thus, consumed higher amounts of acorns. Moreover, they digested proteins present in acorns more efficiently.

These results indicate that large Japanese wood mice can neutralize the toxicity of tannins more effectively and consume acorns more efficiently at lower temperatures. Japanese wood mice survive winter by consuming acorns stored during autumn; therefore, this trait must be advantageous for their overwintering. These findings provide crucial information for predicting changes in habitats and populations of wild animals amid global warming.


Explanation of terms

(*) Plant defense chemical: Among the various chemical compounds naturally present in plants, these compounds are potentially harmful to animals; this potential toxicity deters animals from feeding. These typically include tannins, terpenes, and alkaloids.

(**) Tannins: A collective term for water-soluble polyphenols that strongly bind to proteins. Consumption of a large amount of tannins may result in decreased digestion and renal/hepatic failure.


Photo1: A large Japanese wood mouse carrying an acorn 

Photo1: A large Japanese wood mouse carrying an acorn.

Figure1: Correlation between ambient temperature

Figure1: Correlation between ambient temperature and tannin detoxification in the liver of a large Japanese wood mouse. At 20°C, detoxification required 67.1 min. At 10°C, toxicity was neutralized in only 37.5 min, exhibiting a clear improvement in the detoxification ability (illustration by Makiko Kashiwagi).