Action and perception are complicated by the fact that sensory information is often incomplete. Despite these informational constraints, animals interact intelligently and robustly with the world. Echolocating bats can be assumed to operate under substantial informational constraints as the information acquired by their sonar system is limited and sparse. Nevertheless, they fly swiftly through complex habitats and forage on the wing in complete darkness. Recently, the small tropical bat Micronycteris microtis was documented to glean motionless prey from vegetation. Its ability to precisely localize insects has been interpreted as evidence for the bat acquiring a detailed acoustic image of the target. Given the limitations of the sonar system, it is unclear how this detailed image would be obtained. In this paper, we present a robotic model testing an alternative hypothesis. We propose that echo loudness (differences) contain sufficient information to localize a prey item perched on a leaf. Our robot can localize prey with a precision similar to that of the bat, relying only on echo loudness. We conclude that the documented behavior of M. microtis might not require a detailed acoustic image of the prey.

Echolocating bats can avoid obstacles in complete darkness relying on their sonar system. Under experimental conditions, these animals can infer the 3D position of obstacles. However, in cluttered and complex environments their ability to locate obstacles is likely to be largely reduced, and they might need to rely on more robust cues that do not degrade as the complexity of the environment increases. Here, we present a robotic model of two hypothesized obstacle avoidance strategies in bats, both of which model observed behavior in bats: a Gaze Scanning Strategy and a Fixed Head Strategy. Critically, these strategies only employ interaural level differences and do not require locating obstacles. We found that both strategies were successful at avoiding obstacles in cluttered environments. However, the Fixed Head Strategy performed better. This indicates that acoustic gaze scanning, observed in hunting bats, might reduce obstacle avoidance performance. We conclude that strategies based on gaze scanning should be avoided when little or no spatial information is available to the bat, which corresponds to recent observations in bats.