Animals Make Use of Earth’s Magnetic Field
Magnetoreception is a sense which allows organisms to detect the Earth’s magnetic field. Animals with this sense ranges from fish, amphibians, reptiles, birds, to mammals. The sense is mainly used for orientation and navigation, but it may help some animals to form regional maps.
Migratory Birds - For Orientation
Experiments on migratory birds provide evidence that they make use of a cryptochrome protein in the eye, relying on the quantum radical pair mechanism to perceive magnetic fields. This effect is extremely sensitive to weak magnetic fields, and readily disturbed by radio-frequency interference, unlike a conventional iron compass. Birds have iron-containing short nerve branches in their upper beaks, which may serve as a magnetometer to measure the vector of the Earth magnetic field (intensity and inclination) and also as a magnetic compass, which shows the direction of the magnetic field lines.
Sea turtles
Young sea turtles use the Earth's magnetic field as a source of navigational information during their transoceanic migrations and while homing. The ability of sea turtles to navigate across vast expanses of seemingly featureless ocean has long fascinated biologists. As hatchlings, turtles have never before been in the ocean, but they can use the earth's magnetic field and the direction of ocean waves as crude compasses to guide them offshore into deeper waters favorable for growth and development, and at the same time, maintain them swimming beyond sight of land. Young turtles follow complex migratory pathways that often lead across entire ocean basins and back. Later, as adults, turtles migrate from feeding grounds to specific mating and nesting areas, after which many return to individual feeding sites.
On the other hand, older turtles learn to use magnetic-field information in a far more sophisticated way, as a kind of map that can be used to pinpoint specific areas. It's as if turtles have their own GPS based on magnetism. They have to find a specific beach on which to land, mate, and -- for females -- lay eggs. This all demands considerable accuracy in orientation. Research suggests that mature turtles can distinguish very minor differences in the magnetic field found in different locations, and then make the appropriate course corrections while still far out to sea.
Foxes - For Hunting
Foxes are using the Earth’s magnetic field to hunt. There are stactistic recorded almost 600 mousing jumps, performed by 84 foxes at a wide variety of locations and times. Scientist found that foxes strongly prefer to jump in a north-easterly direction, around 20 degrees off from magnetic north. This fixed heading was important for their success as hunters, and the results are explanation that foxes align their pounces to the Earth’s magnetic field. A red fox could use the Earth’s magnetic field as a “rangefinder”, to estimate the distance to its prey and make a more accurate pounce. This targeting system works because the Earth’s magnetic field tilts downward in the northern hemisphere, at an angle of 60-70 degrees below the horizontal. For example, when hunting a mouse, the fox creeps forward, and listens for the sound of the mouse. It is searching for that sweet spot where the angle of the sound hitting its ears matches the slope of the Earth’s magnetic field. At that spot, the fox knows that it’s a fixed distance away from its prey, and it knows exactly how far to jump to land upon it. This would explain why the direction of the pounce matters most when the prey is hidden.
Extracted from:
https://en.wikipedia.org/wiki/Magnetoreception
https://phys.org/news/2022-07-sixth-animals-earth-magnetic-field.html
https://www.sciencedaily.com/releases/2010/02/100223101419.htm#:~:text=Iron%20containing%20short%20nerve%20branche
s,of%20the%20magnetic%20field%20lines.
https://www.nationalgeographic.com/science/article/foxes-use-the-earths-magnetic-field-as-a-targeting-system#:~:text=They%20found%20that%20foxes%20strongly,for%20their%20success%20as%20hunters.
https://www.sciencedirect.com/science/article/pii/S0960982207008196
https://new.nsf.gov/news/geomagnetic-landmarks-give-turtles-sense-where
