"It's a really tiny magnetic field. It's about 2-2.5 nanotesla at satellite altitude, which is about 20,000 times weaker than the Earth's global magnetic field," Nils Olsen, from the Technical University of Denmark, told BBC News.

The maps on this page use the magnetic unit of a nanoTesla.

If this idea is valid, then plugging the frequency of 150 nanoTesla into a complex physics analysis leads to superlong entanglement times, says Ritz.

The magnetic field, at 150 nanoTesla, was about 300 times weaker than Earth’s magnetic field, so it wouldn’t be expected to confuse the birds in the absence of an entanglement-based navigation system.