The Monarch Butterfly uses it when the sun isn't available: http://en.wikipedia.org/wiki/Monarch_butterfly#Migratory_Theory_Mechanisms http://en.wikipedia.org

The Monarch Butterfly uses it when the sun isn't available: http://en.wikipedia.org/wiki/Monarch_butterfly#Migratory_Theory_Mechanisms http://en.wikipedia.org/wiki/Monarch_butterfly#Migratory_The... Apparently it "sees" the magnetic fields, but it also relies on the sun. I don't think it's been studied if it can reorient itself at birth if the poles are switched or if it's "hardcoded".