Range discrimination by big brown bats (Eptesicus fuscus) using altered model echoes: implications for signal...

Area of Science:

• Bioacoustics
• Animal Behavior
• Sensory Ecology

Background:

• Echolocation is crucial for bats' sensory perception.
• Understanding how bats process echoes informs models of auditory perception.

Purpose of the Study:

• To investigate which acoustic parameters of echolocation signals influence range discrimination in big brown bats (Eptesicus fuscus).
• To test the robustness of bat auditory processing against signal modifications.

Main Methods:

• Modeled echolocation signals of Eptesicus fuscus to create artificial echoes.
• Assessed range discrimination performance using modified and normal signals.
• Systematically altered signal parameters including harmonic energy, duration, frequency sweep, and phase.

Main Results:

• Bats achieved a threshold range discrimination of approximately 0.6 cm at 80 cm.
• Only modifications to the frequency sweep curvature significantly affected ranging performance.
• Most tested signal alterations did not impair the bats' ability to discriminate target ranges.

Conclusions:

• Eptesicus fuscus demonstrates remarkable tolerance to distortions in returning echoes.
• Current echo processing models may not fully account for bats' ability to compensate for signal variations.
• This tolerance might be linked to Doppler shift compensation or natural variations in bat vocalizations.