Echolocating Bats Forge Acoustic Maps for Long Routes

By blindfolding Kuhl's pipistrelle bats and tracking their movements with novel GPS technology, researchers show that the tiny creatures can navigate over several kilometers using only echolocation. The findings highlight the animal's ability to create and use detailed mental acoustic maps of their surroundings. Echolocating bats are known for their ability to nimbly avoid obstacles and catch tiny prey using only sound. However, echolocation is short-ranged and highly directional, allowing for the detection of large objects within only a few dozen meters, limiting its effectiveness for navigation compared to other senses, like vision. Additionally, it is uncertain how well bats can use echolocation to perceive their surroundings in three dimensions or use environmental echoes as landmarks for navigation. Evaluating these questions is made more difficult due to the significant challenges of tracking the small, nocturnal, and highly agile creatures. Thus, whether the animals can rely solely on echolocation to navigate over long distances is unknown. Aya Goldshtein and colleages explored the sensory modalities and navigation strategies of Kuhl's pipistrelle (Pipistrellus kuhlii), a tiny echolocating bat weighing just 6 grams. In a field experiment in Northern Israel, Goldshtein et al. captured and relocated wild bats roughly 3 kilometers from their roosts to 1 of 2 unfamiliar locations within their home range. By depriving the bats' sensory inputs, including vision via blindfolding, while keeping echolocation intact, and tracking the animals using a novel, miniature reverse GPS tracking system in near real-time, Goldshtein et al. examined how the bats navigated back to their roost. The findings show that bats can navigate over several kilometers using only echolocation and that, when available, also use vision to improve navigation performance. Notably, both sighted and blindfolded bats could not sense their roost directly. Initially, bats flew in a meandering pattern, likely to gather acoustic information from their surroundings, before transitioning to a direct flight toward their destination. The observation that distinct and detailed acoustic landmarks guided navigation suggests they use a mental acoustic map of their home range to orient themselves. Moreover, the authors found no evidence that bats use magnetic sensing or olfaction to aid navigation.