Bird navigation may be possible thanks to a sort of superpower or ‘supersense‘ in their eyes, according to new research from Xin Hao at Zhejian University in China.
Recently, scientists have been making many breakthroughs in understanding bird navigation.
For decades, scientists have known the Earth’s magnetic field plays a role in bird migration. However, scientists didn’t know how birds ‘see’ Earth’s magnetic field.
Hao and colleagues found rod-like proteins in pigeon’s eyes. These proteins called MagR contain atoms of iron and sulfur called ferric sulfide clusters.
Previous experiments in 2018 suggested proteins in bird’s eyes are extra-sensitive to the blue wavelength of light. The blue wavelength was previously linked to a bird’s ability to detect magnetic fields, reported Audobon.
Bird Navigation Superpower: Seeing Earth’s Magnetic Field
The MagR protein clusters can fluoresce in a spectrum of three colors. Along the spectrum, one of the colors forms a central peak surrounded by faint “side-peaks,” reports Discover.
“… the fluorescence of ferric sulfide is relatively strong and since it occurs in the retina, it is reasonable to assume the birds can ‘see’ it,” states The Physics arXiv Blog.
When a bird is born, Xin Hao believes the fluorescent atoms in the bird’s eyes become tuned to the Earth’s geomagnetic signature at that location. From that day forward, a peak on the spectrum will remain fixed over the bird’s birthplace – like a pin on a map.
Returning to Home’s Fluorescent Signature
As the bird flies away, the spectrum becomes wider, and a new peak forms reflecting their new location. Possibly, birds may be using their internal bioelectric field to compensate as the home signal becomes weaker.
The further a bird flies from home, the wider the distance between peaks on the spectrum. Then, when it’s time to navigate home, the bird moves in the direction that brings the two peaks together.
Another Bird Navigation Superpower: Magnetoreception
Recently, researchers from the biology, physics, and quantum chemistry fields came together to study bird navigation using magnetoreception.
Their research confirmed that cryptochromes in bird’s eyes display a “quantum mechanical phenomenon,” making them sensitive to magnetic fields. Cryptochromes are sensitive to blue light and are found in plants and animals.
The idea that light-sensitive molecules in a bird’s eye allowed a quantum mechanical phenomenon was first proposed in the late 1970s. Light-sensitive “radical pair” molecules absorb light and spin depending in different directions, depending on the Earth’s magnetic field.
Previous studies showed that birds process magnetic field information in the visual region of their brains. Therefore, the researchers believe birds see the Earth’s magnetic fields. Now, the research from China offers more evidence of how birds see magnetic fields.
See more from nature video:
Kryptonite to Bird Navigation Superpowers
Recently, a study found direct evidence that migratory birds use Earth’s magnetic field like a built-in GPS “to extrapolate their position and get back on course, even when they are blown far afield.”
International researchers exposed reed warblers to electrical fields that mimicked the geomagnetic signature of a faraway city in Russia. However, the birds were in Austria at the time. Tricked, the birds flew as if they believed they were really in Russia, trying to go back to Austria.
Similarly, scientists have interrupted bird’s navigational abilities by placing electromagnetic coils near them. Additionally, other researchers put magnets on the backs of homing pigeons and saw how they became disoriented.
If Xin Hao’s hypothesis is correct, it would further explain why birds are known to become disoriented by changes in magnetic fields. For example, birds sometimes encounter a magnetic field that oscillates at the same frequency as atoms “precess” (spin) in the bird’s eyes. Such encounters may be like Kryptonite to the bird navigation superpower.