Comparative Studies of Food Habits and Digestive Tracts in Two Apodemus Species

Abstract

Feeding experiments using three pairs of food items, analysis of the scaling of digestive organs and microscopic observation were examined in two woodland rodent species, Apodemus argenteus and A. speciosus. Comparing the values of selective indices between acorns and three species of insects, it was shown that A. argenteus has more intensive preference to insects than does A. speciosus. Both the mean ratio of the caecum length to stomach and intestine length (CL/TL) and the ratio of caecum length to the small intestine length (CL/SIL) in A. speciosus were significantly larger than those in A. argenteus. Compared to A. speciosus, distributions of goblet cells stained with PAS in A. argenteus were dense and homogeneous at most of positions of the small intestines. These characteristics in the small intestine suggest that A. argenteus depends on more homogeneous and proteinic foods, and support the results from our feeding experiments. From what described above, it was implied that these differences in potential food habits are related to the characteristics of foraging behavior, habitat utilization and territoriality in the two Apodemus species.