Convincing interpretations on different responses of rodent populations to acorn masting
Acorns, seeds of oak trees, are believed to be staple foodstuff of rodents. Their heat quantity is indeed generally high, but their nutritional compositions vary among species. Some species contain considerable amount of tannins that have toxic effects on animals. Detoxification capability against tannins also varys among rodent species. Therefore, the relationship between acorn masting and rodent dynamics should not easily be generalized. We examine variation of nutritional compositions of acorns and the detoxification capability of rodents in order to get more convincing interpretations on various responses of rodent populations to acorn masting.
Pulse like events of seed crops have great impacts on ecological community, including disease outbreaks, through dynamics of rodent populations. However, the strength of the impacts varys among rodent species. It is, therefore, important for ecosystem management to identify which oak species affects which rodent species. We analyzed the dependency of rodent populations on acorn production and detoxification capability against acorn tannins in three rodent species inhabiting the same forest, and found that the order of the dependency was consistent with detoxification capability against acorn tannins. Our results suggest that physiological information about rodents is essential to interpret responses of rodent populations to acorn masting.