Birds use physical chemistry to find north.
D000818:Animals; D001522:Behavior, Animal; D055592:Biophysical Phenomena; D001703:Biophysics; D001717:Birds / Q000502:physiology*; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D005426:Flight, Animal; D008027:Light; D008280:Magnetics; D008954:Models, Biological