Molecular Versus Microscopic Analyses Tell Different Stories of Little Brown Bat (Myotis lucifugus) Diet in Alaska

Populations of wide-ranging species on the edge of their geographic range may experience environmental conditions unlike those of conspecifics from the core of the range. We conducted a study on the diet of little brown bats (Myotis lucifugus) near the northern edge of their range in Alaska, USA, using molecular fecal dietary techniques and compared these results to a previous diet study using microscopic analysis of the same samples. Molecular dietary analysis suggested that M. lucifugus in this population rely heavily on flies (Diptera), moths (Lepidoptera), and caddisflies (Trichoptera). Our results are consistent with other studies in the insect orders eaten but differ in the relative importance of those orders compared with molecular analyses of diet from M. lucifugus populations nearer the core species range. Our results also contrast with microscopic assessments of diet from these Alaskan samples, which identified spiders (Araneae) as the primary prey item for this population. Importantly, our study demonstrates how different types of analyses can yield different characterizations of diet, even from the same samples.