Migratory birds can actually see Earth's magnetic field.

Migratory birds utilize a biological phenomenon known as magnetoreception to navigate during long-distance flights. This ability is linked to a specific class of proteins called cryptochromes, which are located in the retinas of species like the European robin. These proteins are sensitive to blue light and trigger a quantum chemical reaction when exposed to the Earth's magnetic field.In 2018, researchers from Lund University in Sweden and the University of Oldenburg in Germany identified Cry4 as the likely protein responsible for this 'sixth sense.' When blue light hits these proteins, it creates a pair of radicals with entangled electrons. The orientation of the Earth's magnetic field affects how long these radicals remain in a specific state, which the bird perceives as varying levels of brightness or color across its field of vision.This visual overlay allows birds to see magnetic field lines as a compass superimposed on their surroundings. Studies have shown that if blue light is filtered out, birds often lose their ability to orient themselves correctly. This sophisticated system allows them to travel between continents with an accuracy of just a few miles, even when landmarks are obscured by clouds or darkness.The discovery of cryptochromes has revolutionized our understanding of avian biology and quantum biology. Beyond just robins, similar proteins have been found in the eyes of zebra finches and chickens, suggesting that many bird species share this hidden visual capability. Ongoing research continues to explore how these quantum effects are processed by the bird's brain to create a stable navigational map.