Nonecholocating fruit bats produce biosonar clicks with their wings

Area of Science:

• Evolutionary Biology
• Bioacoustics
• Sensory Systems

Background:

• The evolutionary pathways of complex sensory systems, like bat echolocation, are often unclear due to the vast timescales involved.
• The evolution of bat echolocation is a subject of ongoing scientific debate, with limited understanding of its origins.
• Old World fruit bats have traditionally been classified as non-echolocating, lacking a clear role in echolocation evolution studies.

Purpose of the Study:

• To investigate the orientation mechanisms of Old World fruit bats in complete darkness.
• To explore the potential origins and evolutionary steps of bat echolocation.
• To determine if any Old World fruit bat species exhibit rudimentary forms of echolocation.

Main Methods:

• Behavioral observations of Old World fruit bats in complete darkness.
• Acoustic analysis of sounds produced by bats for orientation.
• Comparative analysis of echolocation mechanisms across bat species.

Main Results:

• Two species of Old World fruit bats were observed using click-like sounds for object detection and discrimination in darkness.
• This click-based echo sensing is rudimentary, lacking accurate distance estimation capabilities found in other echolocating bats.
• These bats generate clicks using their wings, a novel mechanism distinct from the laryngeal or tongue-based echolocation in other bats.

Conclusions:

• Old World fruit bats possess a rudimentary form of echo sensing using wing-generated clicks.
• This wing-clicking behavior, potentially widespread in Old World fruit bats, offers a unique window into the evolution of echolocation.
• While not ancestral to laryngeal echolocation, these 'clicking fruit bats' serve as 'behavioral fossils' for studying sensory system evolution.