Earth’s Magnetic Field Is Like a Compass … But for Birds

Date:10 April 2022 Author: Juandre

Just as the ancient Minoans of Crete used the stars for maritime navigation, birds today migrate with the help of Earth’s magnetic field.

bar tailed godwit, scolopacidae

Bar-tailed Godwit. DEA / C. GALASSOGETTY IMAGES

According to Scientific American, though, we’re getting closer to solving the mystery, which seems to start with the eyes of our feathered friends. SciAm reports that birds can essentially “see” the lines generated by our planet’s magnetic field via a photochemical process that makes them über sensitive to the radical-pair mechanism—which, in theory, explains why magnetic fields affect chemical reactions.

Radical pairs are molecular fragments with unpaired electrons that spin in either an antiparallel pattern (noted with↑↓ and called a singlet state), or a parallel pattern (noted with ↑↑, and called a triplet state). Basically, this means that birds have photoreceptors in their eyes that are sensitive to radical pairs’ photochemical reactions. This—along with inherited abilities from their parents and an internal clock that lets them know when to migrate—allows birds to successfully complete their journeys.

Research has also shown that a bird’s ability to detect a magnetic field perhaps even rivals a human’s ability to use a compass for navigation. Birds are not only able to see a magnetic field, but they can also detect the axis of the field and the angle it creates against Earth’s surface.

digital illustration of migration navigation of birds including the sun, stars, coastlines, earth�s

Digital illustration of migration navigation of birds including the sun, stars, coastlines, and Earth.

DORLING KINDERSLEYGETTY IMAGES

Additionally, birds have two other tools that help them navigate migration: an internal compass that helps them analyze the position of the sun in relation to their location, and the scattered pattern of stars visible at night. In fact, many birds learn where “north” is because they analyze the movement of the stars in relation to the North Star. Even a bird’s sense of smell is crucial to a successful journey—they can tell whether they’ve been somewhere before or not based on familiar scents.

While this research tells us more about the mysterious mechanics of avian migratory patterns, there’s a lot left to learn. One thing we know for certain is that birds are anything but, well, bird-brained.

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