Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Bats use the evening sky’s polarization pattern for orientation


Max Planck scientists discover new sensory capability in a mammal

Animals can use varying sensory modalities for orientation, some of which might be very different from ours. Some bird species for example take the polarization pattern produced by sunlight in the atmosphere to calibrate their orientation systems.

Greater mouse-eared bat taking off.

© MPI f. Ornithology/ Leitner

Bats are watching the sunset from their experimental boxes.

© MPI f. Ornithology/ Leitner

Now researchers from the Max Planck Institute for Ornithology in Seewiesen, Germany, and Queen’s University Belfast have discovered with colleagues from Israel that a night active mammal, the greater mouse-eared bat, has the capability to orient using polarized light. These bats use the polarization pattern of the evening sky to calibrate their inner compass.

In the course of evolution manifold sensory systems developed which allowed animals varying possibilities to perceive their environment. Many insect species for example, but also some fish, amphibians, reptiles and birds can see polarized light. Polarized light forms as a result of sunlight being scattered in the atmosphere.

The sky’s polarization pattern can be used by animals as a compass, well-known examples being the orientation of honeybees, desert ants or migratory birds. Even humans can perceive polarized light to some degree.

Subject to certain conditions we can see a so called Haidinger’s brush, a diffuse yellowish form, which however, has no known function. The fact that mammals can also make use of this sensory perception was not known so far.

An international team of bat researchers including Stefan Greif from the Max Planck Institute for Ornithology, Seewiesen, and from the Queen’s University Belfast now found exactly that.

Their study shows that the greater mouse-eared bat (Myotis myotis) can use the polarized light of the evening sky to calibrate their orientation system, which is based on the Earth’s magnetic field.

The researchers caught 70 female mouse-eared bats in a cave in North-eastern Bulgaria. During dusk they exposed half of the bats to a polarization direction which was shifted 90 degrees from the natural spectrum.

The other half of the animals was placed in similar experimental boxes but with a natural polarization direction. Long after nightfall the bats were brought to two different sites some 20 kilometres away from their home roost. There they were released after the scientists equipped them with tiny radio transmitters to follow their flight trajectories on their way back to the cave.

Those animals that experienced a 90 degrees shifted polarization pattern at sunset, vanished in a direction which deviated about 90 degrees from the control group. With this simple experiment the researchers showed for the first time that bats can use the polarization pattern of the evening sky to calibrate their inner compass for orientation. The precise mechanism however, is still unknown so far.

“Further behavioural and physiological studies are necessary to understand this fascinating new sensory capability”, says Stefan Greif, lead author of this study.


Original publication

Stefan Greif, Ivailo Borissov, Yossi Yovel, Richard A. Holland
A functional role of the sky’s polarization pattern for orientation in the greater mouse-eared bat
Nature Communications, published online 22.07.2014 

Stefan Greif | Max-Planck-Institute
Further information:

Further reports about: Ornithology atmosphere bats orientation polarization sensory sunlight

More articles from Life Sciences:

nachricht Two decades of training students and experts in tracking infectious disease
27.11.2015 | Hochschule für Angewandte Wissenschaften Hamburg

nachricht Increased carbon dioxide enhances plankton growth, opposite of what was expected
27.11.2015 | Bigelow Laboratory for Ocean Sciences

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Climate study finds evidence of global shift in the 1980s

Planet Earth experienced a global climate shift in the late 1980s on an unprecedented scale, fuelled by anthropogenic warming and a volcanic eruption, according to new research published this week.

Scientists say that a major step change, or ‘regime shift’, in the Earth’s biophysical systems, from the upper atmosphere to the depths of the ocean and from...

Im Focus: Innovative Photovoltaics – from the Lab to the Façade

Fraunhofer ISE Demonstrates New Cell and Module Technologies on its Outer Building Façade

The Fraunhofer Institute for Solar Energy Systems ISE has installed 70 photovoltaic modules on the outer façade of one of its lab buildings. The modules were...

Im Focus: Lactate for Brain Energy

Nerve cells cover their high energy demand with glucose and lactate. Scientists of the University of Zurich now provide new support for this. They show for the first time in the intact mouse brain evidence for an exchange of lactate between different brain cells. With this study they were able to confirm a 20-year old hypothesis.

In comparison to other organs, the human brain has the highest energy requirements. The supply of energy for nerve cells and the particular role of lactic acid...

Im Focus: Laser process simulation available as app for first time

In laser material processing, the simulation of processes has made great strides over the past few years. Today, the software can predict relatively well what will happen on the workpiece. Unfortunately, it is also highly complex and requires a lot of computing time. Thanks to clever simplification, experts from Fraunhofer ILT are now able to offer the first-ever simulation software that calculates processes in real time and also runs on tablet computers and smartphones. The fast software enables users to do without expensive experiments and to find optimum process parameters even more effectively.

Before now, the reliable simulation of laser processes was a job for experts. Armed with sophisticated software packages and after many hours on computer...

Im Focus: Quantum Simulation: A Better Understanding of Magnetism

Heidelberg physicists use ultracold atoms to imitate the behaviour of electrons in a solid

Researchers at Heidelberg University have devised a new way to study the phenomenon of magnetism. Using ultracold atoms at near absolute zero, they prepared a...

All Focus news of the innovation-report >>>



Event News

Fraunhofer’s Urban Futures Conference: 2 days in the city of the future

25.11.2015 | Event News

Gluten oder nicht Gluten? Überempfindlichkeit auf Weizen kann unterschiedliche Ursachen haben

17.11.2015 | Event News

Art Collection Deutsche Börse zeigt Ausstellung „Traces of Disorder“

21.10.2015 | Event News

Latest News

Siemens to supply 126 megawatts to onshore wind power plants in Scotland

27.11.2015 | Press release

Two decades of training students and experts in tracking infectious disease

27.11.2015 | Life Sciences

Coming to a monitor near you: A defect-free, molecule-thick film

27.11.2015 | Materials Sciences

More VideoLinks >>>