The Senses/Talk

With the magnetoception, do the birds detect fluctuations in the magnetic field or the magnetic field itself? If they detect fluctuations, then their sense could just be a sub set of the electric field sense (from Maxwell's equations: ∂B/∂t = -curl(E)) what this means is that a changing magnetic field produces an electric field that has a tendancy to rotate (whether that change be due to a moving observer, a moving field, or a changing field, it does not matter). If they detect the magnetic field itself, then it's more likely to be separate. One would have to scan their brain activity under a constant magnetic field and see if there was constant stimulus or stimulus only when the bird moves its head to detect this.--BlackGriffen