Echolocating bats can be divided into guilds according to their preferred habitat and foraging behaviour1-4, which coincide with distinct adaptations in wing morphology5and structure of echolocation signals6. Although coarse structuring of niche space between different guilds is generally accepted, it is not clear how niches differ within guilds7-10, or whether there is fine-grained niche differentiation reflected in echolocation signal structure11,12. Using a standardized performance test, here we show clutter-dependent differences in prey-capture success for bats from five species of EuropeanMyotis.These species are morphologically similar, sympatric13, and all belong to the guild labelled "edge space aerial/trawling foragers"4. We further demonstrate a strong correlation between the prey-detection ability of the species and the respective search-call bandwidth. Our findings indicate that differences in echolocation signals contribute to within-guild niche differentiation. This is the first study relating sensory abilities of a set of potentially competing animal species to a direct measure of their respective foraging performance, suggesting an important role of sensory ecology in the structuring of animal communities.