APPARENT ABSORPTION EFFICIENCY AND GUT MORPHOMETRY OF WOOD-MICE, APODEMUS-SYLVATICUS, FROM 2 DISTINCT POPULATIONS WITH DIFFERENT DIETS

Interpopulation variation in the diet of the wood mouse, Apodemus sylv aticus, is well documented. In this study, we examined the gut morphol ogy and apparent absorption efficiencies of two populations of wood mi ce whose diet in the field was known to differ. One population inhabit ed sand dunes, where food availability was relatively low and the diet was dominated by invertebrates. The other population lived in deciduo us woodland, with greater food availability and a diet consisting prim arily of seeds. Wood mice from the woodland had longer small intestine s and total digestive tract lengths than mice from the sand dunes. How ever, these differences had no effect on the apparent absorption effic iencies of dry mass or energy when the mice were fed meal-worms. wheat grain, or All-Bran diets (apparent energy absorption efficiencies of 88%, 89%, and 65%, respectively). The population differences in gut mo rphometry may be linked to different resource availabilities at the tw o field sites.