Birds Can See Earth's Magnetic Fields

Birds can sense Earth's magnetic field, which allows them to navigate and embark on migration that span tens of thousands of kilometers.

Researchers thought iron-rich cells in birds beaks acted as microscopic compasses, but new studies have found increasing evidence that certain proteins in birds eyes might be what allows them to see magnetic fields.

The studies examined 39 zebra finches and European robins, both single out a protein called Cry4 ( cryptochromes), a light-sensitive protein found in the retina. The team found that while levels of Cry1 and Cty2 rose and fell over the day Cry4 levels remained constant, indicating the protein was being produced steadily.

This is the first time that such a molecule has been identified in animals. A specific molecule that is responsible for the detection of magnetic fields, Cry4 is a protein responsible for biological sleep cycles, but also thought to react to Earth's magnetic field thanks to quantum mechanics.

The protein's quantum interaction could help birds sense this field. Previous studies have suggested that birds use quantum theory to literally 'see' Earth's magnetic field as they fly through the sky different reactions are produced in the eyes of all avian creatures depending on which way Earth's magnetic field is spinning. These reactions could create a picture of the fild in different shades across the bird's eye, such an image would not be a clear outline of a shape, but just shades of dark and light depending on how the field moves. When a light photon enters the bird's eye, it comes into contact with the cryptochrome and is given an energy boost which puts it into quantum entanglement a state where the electons are spatially separated, but still able to interact with affect one another.

In humans, photoreceptive cones consist of three types, each cone is sesitive to red, green, or blue light (called trichromatic color vision).

Birds have an extra cone for tetrachromatic color vision, this extra cone expands the visible light spectrum and allows birds to see ultraviolet frequencies.