Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

After the next sunset, please turn right

30.03.2010
Bats navigate with the help of the sun

Despite the fact that bats are active after sunset, they rely on the sun as their most trusted source of navigation. Researchers from the Max Planck Institute for Ornithology found that the greater mouse-eared bat orients itself with the help of the earth's magnetic field at night and calibrates this compass to the sun's position at sunset (published online in Proceedings of the National Academy of Science, PNAS, March 29th, 2010)


Greater Mouse-Eared Bat (Myotis myotis)
Image: Stefan Greif


Greater Mouse-Eared Bat (Myotis myotis)
Image: Dietmar Nill

Since the 1940s it has been known that bats use echolocation calls for orientation at close range. Some bats, however, fly 20 km and more away from their roost every night to search for prey. Summer and winter roosts are often over 50 km apart and some species migrate even up to 1000 km each year across Europe. Recent evidence has shown that bats utilise the Earth's magnetic field for orientation on longer journeys. Scientists of the Max Planck Institute for Ornithology have now confirmed this finding after conducting research on the ability of greater mouse-eared bats to find their way home at night after manipulations of the magnetic field at sunset.

First, Richard Holland, Ivailo Borissov and Björn Siemers wanted to discover if bats are able to orient themselves at an unknown location. To do so, they captured bats and released them 25 km from their roost cave. They followed their flights with the help of small radio transmitters. Already at 1-3 km distance, most bats were heading home in the direction of their cave. "I was quite sceptical that this first part of the experiment would work," says Björn Siemers. "Therefore I was very impressed that the fastest bats arrived back in their cave only two hours after release". The precise question the researchers wanted to answer was: is this ability for orientation in unknown territory somehow related to perception of the magnetic field? And, further to this, do the bats then calibrate their magnetic compass to the sun like migrating birds?

The three researchers altered the direction of the magnetic field from north to east for half of the bats during sunset with the help of a device called a Helmholtz coil. And in contrast to the control group, these bats flew about 90 degrees east instead of south to their home cave. The decisive last part of the experiment was to repeat the procedure at night. Again the magnetic field of half of the bats was turned from north to east, but only after all signs of sunset had vanished from the sky. In this case the bats with an altered magnetic field flew in the same direction as the control bats. "The manipulation of the magnetic field was only effective in combination with the sunset", says Richard Holland. "Greater mouse-eared bats used the position of the sun at sunset as the most reliable indication of direction, and calibrated the magnetic field with it to use it as a compass later that night". For the bats, sunset means west, regardless to what their actual magnetic field is telling them. Due to iron deposits in the local earths crust, the magnetic field is known to vary unpredictably. It seems therefore that the animals find the sun to be a more trustworthy source for direction. This result is remarkable, given that this species usually emerges from their caves after sunset. "After the bats became active, we were able to see where the sun had disappeared even an hour after sunset", says Björn Siemers. This 'glow' seemed to be sufficient for the bats orientation. [SP]

Original work:
Richard Holland, Ivailo Borissov and Björn Siemers
A nocturnal mammal, the greater mouse-eared bat, calibrates a magnetic compass by the sun

Proceedings of the National Academy of Sciences (PNAS). Published online March 29th, 2010

Contact:
Dr. Richard Holland
Max Planck Institute for Ornithology, Radolfzell
Phone: +49 (0) 7732 1501 - 23
E-mail: rholland@orn.mpg.de
Dr. Björn Siemers
Max Planck Institute for Ornithology, Seewiesen
Phone: +49 (0) 8157 932 - 348
E-mail: siemers@orn.mpg.de

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

More articles from Life Sciences:

nachricht Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery
20.01.2017 | GSI Helmholtzzentrum für Schwerionenforschung GmbH

nachricht Seeking structure with metagenome sequences
20.01.2017 | DOE/Joint Genome Institute

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Helmholtz International Fellow Award for Sarah Amalia Teichmann

20.01.2017 | Awards Funding

An innovative high-performance material: biofibers made from green lacewing silk

20.01.2017 | Materials Sciences

Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery

20.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>