How do rousette bats use echolocation differently from most small bats?

Unlike most small bats (suborder Microchiroptera), which use echolocation for a wide range of activities including hunting prey, navigation, and obstacle avoidance, rousette bats (genus Rousettus) have independently evolved a parallel echolocation system used exclusively for obstacle avoidance.12

While microchiropteran bats rely on echolocation as their primary sensory tool for tracking and capturing flying or terrestrial prey, rousette bats—which belong to the suborder Megachiroptera—primarily rely on their well-developed vision to navigate and locate food. Consequently, the echolocation system in Rousettus is a specialized adaptation that allows them to orient themselves acoustically in dark environments, such as caves, where they roost, rather than as a comprehensive system for foraging.134