Jamming avoidance response of big brown bats in target detection

Area of Science:

• Bioacoustics
• Animal Behavior
• Sensory Ecology

Background:

• Big brown bats (Eptesicus fuscus) use frequency-modulated (FM) echolocation calls for hunting.
• The constant-frequency (CF) tail of their calls is crucial for extending sonar range.
• This CF component may be susceptible to interference from other bats' echolocation signals.

Purpose of the Study:

• To investigate how bats alter their echolocation calls in response to interfering acoustic stimuli.
• To determine if bats exhibit jamming avoidance behavior.

Main Methods:

• Bats performed a laboratory detection task using echolocation.
• Echolocation calls were recorded and analyzed with and without a constant-frequency (CF) jamming tone.
• Behavioral responses to varying jamming frequencies were observed.

Main Results:

• Bats shifted the CF component of their echolocation calls away from the jamming frequency when it was within 2-3 kHz of their baseline frequency.
• This avoidance response was bidirectional, moving away from the interfering tone.
• No significant changes in call duration were observed between jamming and no-jamming conditions.

Conclusions:

• Bats actively modify their echolocation signals to avoid acoustic interference from conspecifics.
• The jamming avoidance response likely prevents masking and maintains effective prey detection.
• This behavior highlights the importance of the CF component in bat sonar and inter-bat communication.