Daubenton's bats maintain stereotypical echolocation behaviour and a lombard response during target interception in...

Area of Science:

• Sensory Ecology
• Animal Behavior
• Bioacoustics

Background:

• Bats primarily use echolocation for nocturnal insect hunting.
• Despite this, bats possess complex visual systems, raising questions about vision's role.
• The function of vision in echolocating bats, especially under challenging conditions, remains unclear.

Purpose of the Study:

• To investigate if visual cues reduce reliance on echolocation in bats during acoustic noise.
• To test the hypothesis that visual availability influences echolocation behavior in Myotis daubentonii.
• To understand the interplay between vision and echolocation in a nocturnal insectivorous bat.

Main Methods:

• Five wild-caught Myotis daubentonii bats were trained to land on a target.
• Experiments were conducted in silence and broad-band noise conditions.
• Light intensity and spectrum were manipulated during trials.

Main Results:

• Bats were nearly three times more likely to need multiple attempts in noise versus silence.
• Bats displayed a Lombard response (0.18 dB/dBnoise) and reduced call intervals during noise.
• Echolocation behavior adjustments did not differ between light and dark conditions.

Conclusions:

• Bat echolocation is a hard-wired system with stereotyped compensation for noise and range.
• Visual cues do not alter echolocation behavior under challenging acoustic conditions.
• Individual variations in behavioral adjustments suggest flexibility possibly involving higher-order processing.