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Bird’s eye view

Robin+%28CC+BY-SA+2.0%29
Robin (CC BY-SA 2.0)

Robin (CC BY-SA 2.0)

Richard Leeming

Richard Leeming

Robin (CC BY-SA 2.0)

Jacob Wall, ECU Reporter

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Scientists have wondered for decades on how birds are able to navigate home from unfamiliar places or correctly migrate to areas tens of thousands of kilometres away.

Studies of magnetic coils or scent deprivation have shown birds use a variety of clues from the environment around them in order to find their way home.

It also had been made apparent that birds have the ability to see Earth’s magnetic field.

A magnetic field is a thing within the neighbourhood of either a magnet or electrical current. Magnetic fields like the one on Earth, cause permanent magnets like the one within a compass needle (the north end of a tiny magnet) to point towards the south magnetic pole present at the geographic north of our Earth.

The earth’s magnetic field is obviously unable to be seen by the human eye, however birds know what it looks like, but what it looks like to them, nobody knows.

A 2018 study showcased by ScienceNews.org, explains how a newly discovered protein in the eye of birds, allows them to see Earth’s magnetic field.

This idea came from two studies, one on zebra finches, and the other on European robins. Both these papers highlighted the new protein, which has been called Cry4 and is part of a protein class named cryptochromes.

Cryptochromes are photoreceptors that are sensitive to blue light.

Photoreceptors are located in the back part of the eye known as the retina. They are specialised cells that respond to light.

Cry4 gives birds the ability to orient themselves by detecting the magnetic fields. This idea, named magnetoreception, is known as a bird’s ‘sixth sense’.

For years, science and bird researchers believed the iron-rich cells found in a bird’s beak is what acted as the microscopic compass, giving them their navigation abilities. But now it seems that avian (bird) magnetorecption is dependent on blue light, which confirms that a bird’s navigation mechanism is in fact a visual one, not one found in the beak.

Researchers from universities in Sweden and Germany studied zebra fiches and European robins respectively in order to gather further evidence. Both research teams made some interesting findings in regards to this bird study. They discovered that protein Cry4 is clustered in an area of the retina that receives a large amount of light. This makes sense, as magnetorecption is heavily dependent on light.

More specifically, the German researches found that the European robins have increased Cry4 contents throughout the migratory season in comparison to a chicken going through a non-migratory season.

The research teams believe the evidence is strong, but agree to it not being definitive and caution that more research is needed in order to confirm Cry4 as being the correct protein responsible for magnetorecption, since Cry1 and Cry2 have been found to be responsible in other species, such as the garden warbler bird.

“We have quite a lot of evidence, but Cry4 is not proven,” states Henrik Mouritsen, an animal navigation expert part of the German, European robin study research team.

Perhaps a better conclusion to this study may come from observing birds that are known to not contain functioning Cry4 protein, to see if they also have an internal compass, and discovering what it may be.

Since cryptochromes are a protein class only found in plants and animals, its impossible for the human eye to interpret light the same way as birds do, thus not allowing us to see Earth’s magnetic field.

If a new study was to be released that discovered a new protein in the human eye or a new method of vision, which now allowed for humans to see magnetic fields surrounding Earth, then we could use this new enhanced sense to monitor the Earth. We would be able to see disruptions in the magnetic field, disruptions which cause natural disasters such as earthquakes and tsunamis. This could allow humans to become more cautious when it comes to the world’s natural environmental problems, and give our race a chance to remain safe.

University of Oxford chemist and bird researcher, Peter Hore said, “we still may not understand how birds actually perceive magnetic fields. To know, you’d have to be a bird.”

In 2018, this statement seems to be an accurate one, as no forms of study have surfaced revolving around ideas like transferring Cry4 protein into the human eye for example, that could allow humans (especially scientists and researchers) to visualise for themselves what birds do see.

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Bird’s eye view