I've never seen this myself, however. Also, I don't know how useful this would be for direction finding. I can see that the effect would be useful for figuring out the direction of the sun on a cloudy day, but accounts indicate that the Haidinger's Brush effect is pretty small and easy to miss.
But if humans can see it, more or less by accident, it's not much of a stretch to imagine than animals are much more sensitive to it.
https://www.polarization.com/haidinger/haidinger.html
I've never seen this myself, however. Also, I don't know how useful this would be for direction finding. I can see that the effect would be useful for figuring out the direction of the sun on a cloudy day, but accounts indicate that the Haidinger's Brush effect is pretty small and easy to miss.
But if humans can see it, more or less by accident, it's not much of a stretch to imagine than animals are much more sensitive to it.