Disorientation of inexperienced young pigeons after transportation in total darkness

Abstract

Leask's proposal¹ that magnetic field detection in birds is accomplished by an optical double-resonance process in the rhodopsin molecules in the retina, a spatially well ordered cellular array, is intriguing. Being an axial rather than a polar phenomenon, it is consistent with observations that birds do not make use of the polarity of the magnetic field². The hypothesis nevertheless requires that light is necessary for sensing magnetic fields, which has prompted us to perform the homing experiments with pigeons reported here. It is known that transportation in a distorted magnetic field causes an increase in scatter, frequently even random, in the initial orientation of young pigeons^3–6, and we sought to discover whether transportation in total darkness would have a similar effect. The results are consistent with Leask's hypothesis but their explanation is not unambiguous. Plainly, however, transportation in total darkness, like the disruption of magnetic or olfactory^3,7 information en route, is another way of preventing the collection of meaningful orientation information during the outward journey to the release site.