What is the fundamental mechanism by which radical pairs enable magnetoreception in migratory birds, including the role of electron spin and hyperfine interactions?

Radical pairs, which are two molecules each possessing an unpaired electron, are believed to be the basis for magnetoreception in migratory birds. The mechanism relies on the fact that the spins of the unpaired electrons in the radical pair can be either correlated (in a singlet state) or uncorrelated (in a triplet state). The interconversion between the singlet and triplet states is influenced by the Earth's magnetic field. The key lies in hyperfine interactions, which are the interactions between the electron spins and the nuclear spins of nearby atoms, such as hydrog....