Visual cues enhance obstacle avoidance in echolocating bats

Abstract

Studies have shown that bats are capable of using visual information for a variety of purposes, including navigation and foraging, but the relative contributions of visual and auditory modalities in obstacle avoidance has yet to be fully investigated, particularly in laryngeal echolocating bats. A first step requires a characterization of behavioral responses to different combinations of sensory cues. Here we quantify the behavioral responses of the insectivorous big brown bat, Eptesicus fuscus, in an obstacle avoidance task offering different combinations of auditory and visual cues. To do so, we utilize a new method that eliminates the confounds typically associated with testing bat vision and precludes auditory cues. We find that the presence of visual and auditory cues together enhances bats’ avoidance response to obstacles compared to cues requiring either vision or audition alone. Analysis of flight and echolocation behaviors, such as speed and call rate, did not vary significantly under different obstacle conditions, and thus are not informative indicators of a bat's response to obstacle stimulus type. These findings advance the understanding of the relative importance of visual and auditory sensory modalities in guiding obstacle avoidance behaviors.

Sensory error drives fine motor adjustment

“…The contribution of nonauditory sensory information to bat echolocation has been underestimated in general. Apart from a few studies that investigated the role of vision in modulating echolocation behavior of bats ( 37 – 39 ), there are scarce data on the potential role of other sensory modalities in bat sonar navigation. Although there is evidence for the contribution of somatosensory feedback to bat flight control ( 40 , 41 ), the role of somatosensory feedback in bat vocal control has not been studied despite its long-suggested importance in mammals ( 26 ).…”

Ecomorphological correlates of inner and middle ear anatomy within phyllostomid bats

“…Wing aspect ratio (the proportion of wingspan to wing area) has been proposed as an indicator of habitat use (Crane et al, 2022;Norberg & Rayner, 1987); lower aspect ratios (e.g., short, wide wings) are found in species that navigate cluttered habitats, and high aspect ratios in species that navigate the canopy and/or open habitats. As such, an inverse relationship between aspect ratio and call frequency could be expected (Jacobs et al, 2007;Jones & Barlow, 2004).…”

“…This is thought to reflect the fundamental trade-off between spatial resolution and call frequency (see above), which would render small targets (length < 5.0 mm) undetectable at low frequencies (below $30 kHz). This same trade-off may also govern the relationship between call frequency and habitat use; for example, lower call frequencies (and thus longer call wavelengths) maximize call distance and increase a bat's opportunity to detect and avoid obstacles in open habitats, and vice versa (Gordon et al, 2019;Jacobs et al, 2007;Jones & Barlow, 2004). Wing aspect ratio (the proportion of wingspan to wing area) has been proposed as an indicator of habitat use (Crane et al, 2022;Norberg & Rayner, 1987); lower aspect ratios (e.g., short, wide wings) are found in species that navigate cluttered habitats, and high aspect ratios in species that navigate the canopy and/or open habitats.…”

Night skies through animals’ eyes—Quantifying night-time visual scenes and light pollution as viewed by animals

“…Such objects, including predators or prey that sparsely emit sound or odors, are almost impossible to localize without vision–except with active sensing ( Nelson and MacIver, 2006 ). And even species with active sensing alternatives, such as bats, use vision for obstacle control ( Jones and Moss, 2021 ). One behavior in particular that cannot be executed with other passive senses, is flight ( Davies and Green, 1994 ).…”