Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

How barbastelle bats trick moths that are able to hear their echolocation calls

14.03.2018

In the evolutionary arms race between bats and their insect prey, some moths have developed ears to detect echolocating bats and avoid being caught. Conversely, barbastelle bats are known to counter moth hearing by using quiet, 'stealthy' calls to search for prey in the dark.

Recording the hunting behaviour of this intriguing species, researchers have now found that barbastelle bats sneak up on unsuspecting moths by gradually emitting even fainter calls as they come closer.


A barbastelle bat with its characteristic bumpy face

Daniel Lewanzik / MPIO

The barbastelle bat, with its characteristic bumpy face, is a very successful hunter that manages to almost exclusively feed on eared moths. Comparable with stealth fighter jets, barbastelle bats use a 'stealth echolocation' tactic - echolocation at intensities that are inaudible to distant moths - to ambush prey. Their calls are more than 10 times quieter than those of other bats which hunt insects in the same way.

Upon detecting a nocturnal moth, this intriguing bat species reduces its call intensity even further while closing in, according to new research by ecologists at the Max Planck Institute for Ornithology in Germany.

Consequently, call intensity heard by the moth only increases very slowly, delaying the time and shortening the distance at which it becomes aware of the attacker. Once a moth hears the calls, it is most likely too late to escape.

"Barbastelle bats call with surprisingly low intensity, usually a characteristic of species that hunt in cluttered habitats and need to avoid distracting echoes from branches and leaves. Low intensity calls come at a cost though. They do not reach far and as a result, insects can only be detected from a close distance," says Dr Daniel Lewanzik from the Max Planck Institute of Ornithology.

To test why the barbastelle can catch eared moths when other bats cannot, the authors closely investigated echolocation behaviour during pursuit and final attack.

They tethered moths (Noctua pronuba) to a long fishing rod with a miniature microphone positioned a few centimetres above, offering them to free-ranging barbastelle bats in a forest and to captive ones in a flight room. This allowed the team to analyse the echolocation calls from a moth's perspective. Simultaneously, the researchers recorded the calls of approaching bats with a four-microphone array in order to reconstruct three-dimensional flight paths and thus measure their distance to the moths.

Barbastelle bats can detect moths at about 1.6 m distance. Once approaching their unsuspecting prey, the bats lower their already faint calls by 4 decibels (dB) or 40% for each halving of distance. During the final buzz when they are less than 1 m away, call intensity decreases by more than 6 dB or 50% per halving of distance*.

Echolocation call levels received by the moths remain almost constant during the attack (instead of doubling per halving of distance) as a result of the bats' stealth tactic, keeping them low enough to prevent the moth from escaping.

"Our results suggest that barbastelle bats are able to outwit the hearing defence of moths and close in without triggering any last-ditch manoeuvres, making them very successful moth hunters, " concludes Dr Holger Goerlitz, also from the research institute. "In fact, the evolution of moth ears might benefit barbastelles as they can avoid competition with other, louder bats."


For more information on this study, please contact the authors:

Dr Daniel Lewanzik, Max Planck Institute for Ornithology, Email: dlewanzik@orn.mpg.de, Tel: +49 8157 932 378
Dr Holger Goerlitz, Max Planck Institute for Ornithology, Email: hgoerlitz@orn.mpg.de, Tel: +49 8157 932 372

To request a pdf copy of the study and/or audiovisual material, please contact:

Sabrina Weiss, Press Officer, British Ecological Society, Email: press@britishecologicalsociety.org, Tel: +44 207 685 2523
Or:
Dr. Sabine Spehn, Press Officer, Max Planck Insitute for Ornithology
Email: pr_seewiesen@orn.mpg.de, Tel. +49 8157 932421

Weitere Informationen:

http://onlinelibrary.wiley.com/wol1/doi/10.1111/1365-2435.13073/full (with end of embargo time freely available for four weeks)

Dr. Sabine Spehn | Max-Planck-Institut für Ornithologie
Further information:
http://www.orn.mpg.de

Further reports about: Max-Planck-Institut bats echolocation echolocation calls moths

More articles from Life Sciences:

nachricht Climate Impact Research in Hannover: Small Plants against Large Waves
17.08.2018 | Leibniz Universität Hannover

nachricht First transcription atlas of all wheat genes expands prospects for research and cultivation
17.08.2018 | Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Color effects from transparent 3D-printed nanostructures

New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference

Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

LaserForum 2018 deals with 3D production of components

17.08.2018 | Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

 
Latest News

Smallest transistor worldwide switches current with a single atom in solid electrolyte

17.08.2018 | Physics and Astronomy

Robots as Tools and Partners in Rehabilitation

17.08.2018 | Information Technology

Climate Impact Research in Hannover: Small Plants against Large Waves

17.08.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>