Spatial perception and adaptive sonar behavior

Abstract

Bat echolocation is a dynamic behavior that allows for real-time adaptations in the timing and spectro-temporal design of sonar signals in response to a particular task and environment. To enable detailed, quantitative analyses of adaptive sonar behavior, echolocation call design was investigated in big brown bats, trained to rest on a stationary platform and track a tethered mealworm that approached from a starting distance of about 170 cm in the presence of a stationary sonar distracter. The distracter was presented at different angular offsets and distances from the bat. The results of this study show that the distance and the angular offset of the distracter influence sonar vocalization parameters of the big brown bat, Eptesicus fuscus. Specifically, the bat adjusted its call duration to the closer of two objects, distracter or insect target, and the magnitude of the adjustment depended on the angular offset of the distracter. In contrast, the bat consistently adjusted its call rate to the distance of the insect, even when this target was positioned behind the distracter. The results hold implications for understanding spatial information processing and perception by echolocation.

It's not black or white—on the range of vision and echolocation in echolocating bats

“…In addition, echolocation also provides much more accurate estimations of the distance of an object, its velocity (calculated by integrating several echoes) and sometimes even the distance of the background behind it (Aytekin et al, 2010; Melcón et al, 2011). …”

Adaptive vocal behavior drives perception by echolocation in bats

“…Aytekin et al [20] monitored the echolocating bat’s adaptive sonar tracking behavior under controlled conditions. Big brown bats were trained to track an approaching tethered target from a stationary platform in the presence of a distracter, which was introduced at different distances and angular offsets from the approaching target.…”

Dynamic adjustment of echolocation pulse structure of big-footed myotis (Myotis macrodactylus) in response to different habitats

“…For example, a number of species have been shown to respond to highly cluttered versus uncluttered space by increasing pulse peak frequencies and decreasing pulse durations (e.g., M. septentrionalis- Broders et al, 2004;M. lucifugus-Wund, 2006; Pipistrellus pygmaeus- Bartonicka and Rehak, 2005;Macrophyllum macrophyllum-Brinkløv et al, 2010), which may improve the accuracy of the bat's spatial resolution of objects (Altes and Skinner, 1977;Simmons and Stein, 1980;Aytekin et al, 2010). Additionally, the frequency sweeps of most search phase pulses in vesper bats were sigmoidal in shape, which may have a combination of different functions, making the signals Doppler tolerant (Kalko and Schnitzler, 1989) and while still containing target information (Simmons and Stein, 1980).…”