Featured Research

from universities, journals, and other organizations

Bats use polarized light to navigate: First mammal known to use polarization patterns in the sky to navigate

Date:
July 22, 2014
Source:
Natural Environment Research Council
Summary:
The bats use the way the sun's light is scattered in the atmosphere at sunset to calibrate their internal magnetic compass, which helps them to fly in the right direction, a new study has shown.

Greater mouse-eared bat.
Credit: merial / Fotolia

Scientists have discovered that greater mouse-eared bats use polarisation patterns in the sky to navigate -- the first mammal that's known to do this.

The bats use the way the Sun's light is scattered in the atmosphere at sunset to calibrate their internal magnetic compass, which helps them to fly in the right direction, a study published in Nature Communications has shown.

Despite this breakthrough, researchers have no idea how they manage to detect polarised light.

"We know that other animals use polarisation patterns in the sky, and we have at least some idea how they do it: bees have specially-adapted photoreceptors in their eyes, and birds, fish, amphibians and reptiles all have cone cell structures in their eyes which may help them to detect polarisation," says Dr Richard Holland of Queen's University Belfast, co-author of the study.

"But we don't know which structure these bats might be using."

Polarisation patterns depend on where the sun is in the sky. They're clearest in a strip across the sky 90 from the position of the sun at sunset or sunrise.

But animals can still see the patterns long after sunset. This means they can orient themselves even when they can't see the sun, including when it's cloudy. Scientists have even shown that dung beetles use the polarisation pattern of moonlight for orientation.

A hugely diverse range of creatures -- including bees, anchovies, birds, reptiles and amphibians -- use the patterns as a compass to work out which way is north, south, east and west.

"Every night through the spring, summer and autumn, bats leave their roosts in caves, trees and buildings to search for insect prey. They might range hundreds of kilometres in a night, but return to their roosts before sunrise to avoid predators. But, until now, how they achieved such feats of navigation wasn't clear," says Stefan Greif of Queen's University Belfast, lead author of the study.

Even so, previous studies suggested that bats might detect polarisation patterns when they emerge from their caves at dusk.

"Most people are familiar with bats using echolocation to get around. But that only works up to about 50 metres, so we knew they had to be using another of their senses for longer range navigation," says Greif.

In a bid to shed light on the matter, Holland, Greif and colleagues from Tel Aviv University showed 70 adult, female mouse-eared bats one of two different types of polarisation patterns at sunset.

They then took them to one of two release sites in Bulgaria about 20 to 25 kilometres from their home roost. They released the bats at 01:00 AM -- when no polarisation is visible -- and followed the direction they set off in using small radio transmitters attached to their backs.

They found the bats that had been shown a shifted pattern of polarised light headed off in a direction shifted at right angles from the controls released at the same time.

Bats probably use a suite of senses, including the position of the Sun or the stars, Earth's magnetic field, smells, sight, and of course, echolocation to navigate.

Many bat species are declining across Europe, despite being protected. Ironically, wind turbines are seriously harming their populations.

"We know that bats must be 'seeing' the turbines, but it seems that the air pressure patterns around working turbines give the bats what's akin to the bends," says Holland.

"It's most common in migratory species, with around 300,000 bats affected every year in Europe alone. You just find bats dead at the bottom of these turbines. One option is to reduce turbine activity during times of peak migration."

Bats provide a vital service that tends to be overlooked -- they're natural pest controllers. It's estimated that they save us millions of pounds in pesticides by eating insects.

"Anything we can do to understand how they get about, how they move and navigate will be step forward in helping to protect them," adds Holland.

The study was funded by a Natural Environment Research Council grant to Richard Holland and by the Max Planck Society.


Story Source:

The above story is based on materials provided by Natural Environment Research Council. Note: Materials may be edited for content and length.


Journal Reference:

  1. 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, 2014; 5 DOI: 10.1038/ncomms5488

Cite This Page:

Natural Environment Research Council. "Bats use polarized light to navigate: First mammal known to use polarization patterns in the sky to navigate." ScienceDaily. ScienceDaily, 22 July 2014. <www.sciencedaily.com/releases/2014/07/140722111838.htm>.
Natural Environment Research Council. (2014, July 22). Bats use polarized light to navigate: First mammal known to use polarization patterns in the sky to navigate. ScienceDaily. Retrieved September 22, 2014 from www.sciencedaily.com/releases/2014/07/140722111838.htm
Natural Environment Research Council. "Bats use polarized light to navigate: First mammal known to use polarization patterns in the sky to navigate." ScienceDaily. www.sciencedaily.com/releases/2014/07/140722111838.htm (accessed September 22, 2014).

Share This



More Plants & Animals News

Monday, September 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: San Diego Zoo Welcomes Cheetah Cubs

Raw: San Diego Zoo Welcomes Cheetah Cubs

AP (Sep. 20, 2014) The San Diego Zoo has welcomed two Cheetah cubs to its Safari Park. The nearly three-week-old female cubs are being hand fed and are receiving around the clock care. (Sept. 20) Video provided by AP
Powered by NewsLook.com
Chocolate Museum Opens in Brussels

Chocolate Museum Opens in Brussels

AFP (Sep. 19, 2014) Considered a "national heritage" in Belgium, chocolate now has a new museum in Brussels. In a former chocolate factory, visitors to the permanent exhibition spaces, workshops and tastings can discover derivatives of the cocoa bean. Duration: 01:00 Video provided by AFP
Powered by NewsLook.com
Could Grief Affect The Immune Systems Of Senior Citizens?

Could Grief Affect The Immune Systems Of Senior Citizens?

Newsy (Sep. 19, 2014) The study found elderly people are much more likely to become susceptible to infection than younger adults going though a similar situation. Video provided by Newsy
Powered by NewsLook.com
Jury Delivers Verdict in Salmonella Trial

Jury Delivers Verdict in Salmonella Trial

AP (Sep. 19, 2014) A federal jury has convicted three people in connection with an outbreak of salmonella poisoning five years ago that sickened hundreds of people and was linked to a number of deaths. (Sept. 19) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins