Myotis myotis is a gleaner. Its main prey are ground beetles of the family Carabidae, along with crickets and other large arthropods that move on the surface. It flies slowly, low over short-grazed pasture, forest floor or freshly mown ground.
Echolocation is poorly suited to picking a beetle out from the acoustic clutter of the ground itself, so the bat listens instead. The rustling of a beetle's legs on leaf litter or soil is a strong, unambiguous cue, and passive listening plays a large part in the final approach. This is why the species depends on habitats with sparse, low ground cover: tall dense vegetation both hides the sound and blocks the landing.
The conservation implication follows directly from the hunting method. Agricultural intensification that removes grazed pasture and hedgerow-bordered meadow removes the surfaces this bat can hunt on, even where insect numbers elsewhere remain adequate. Colonies also depend on large undisturbed attic spaces, which makes building renovation a real constraint on the species.