"A quantum effect known as entanglement may be part of the compass that birds use to sense Earth’s magnetic field, researchers report in an upcoming Physical Review Letters.

Critters from bacteria to mole rats use tiny variations in the Earth’s magnetic field to navigate, but exactly how they sense the magnetism is a mystery. One idea is that magnetic fields disrupt pairs of entangled electrons in a light-sensitive protein in the retina. In quantum entanglement, particles are linked to each other so that one always knows instantly what the other is doing, even if they get separated."

"Scientists say the magnetic north pole is moving toward Russia and the fallout has reached -- of all places -- Tampa International Airport.

The airport has closed its primary runway until Jan. 13 to repaint the numeric designators at each end and change taxiway signage to account for the shift in location of the Earth's magnetic north pole."

"Cryptochrome-mechanism:
It's about a chemical reaction between the chromophor Flavin Adenine Dinucleotide (FAD) and a Tryptophan amino acid (Trp324, Trp377 or Trp400).
Blue light excites the FAD, which gets an electron from Trp, which turns it into a radical.
Now here's the deal: Without magnetic field Singulett- and Triplett-states are mixed (1:3). But with magnetic field, the Zeeman-effect shifts the energy-levels of the states T+1 and T-1. Only S and T0 intermix (1:1).
Wigners selection principle determines which chemical reactions are possible, so the shift from 3:1 to 1:1 leads to different ratios of chemical products.

magnetite-mechanism:
A tiny spheric magnetite-particle is stifly attached to the cell membrane of neurons. Depending on the magnetic field, different forces force the magnetite in either direction, mechanicaly opening and closing ion channels in the membrane, like valves. Open valve: signal. Closed valve: no signal."

I've read these and other studies. I'm wondering about any studies that look at long term natural variations in the magnetic field and how they correlate with long term variations in bird migration patterns, i.e., if there are three major U.S. flyways, have the dimensions of those flyways changed with changes in the magnetic fields? Or, does the presence of coastlines (in the case of the eastern and western flyways) or the presence of a large river system (the Mississippi) provide sufficient navigation tools for migratory behavior over the long term.