Can Migrating Birds See True North? or, Birds have Super Magno-Eyes.

The question of just how birds figure out where they're going when they're migrating is an old one. At least I think it is. Is it genetically based, like in Monarch butterflies? Or do they just wing it? (Ha, no pun intended, I swear.)Do they literally "see" what direction they are headed? It has long been a schoolboy daydream among ornithologists that maybe, just maybe birds can sense the magnetic field of the earth through their eyes (once again, I can only guess at what ornithologists really daydream about.)Some recent research tentatively points out that in some birds, this magno-sight may be the case.

In a study conducted at the University of Oldenburg, scientists injected some migratory garden Warblers' eyes and brain with a molecular tracer capable of traveling along nerve fibers. When they let the birds go and orient themselves, the tracers converged on a spot in the brain (the thalamus -- vision). This led them to surmise that maybe the birds see the magnetic fields that they have long been known to align themselves with. The real interesting point of all this is that both of the tracers, one injected, as noted, in the eye, and another, in cluster N (an area very active when orienting) converged in a part of the brain where vision is registered and sorted out. This also shows a direct linkage between the eyes and cluster N. Does this link mean that when birds need it, there is a little pointer in their sight that shows true North? Is it always present, or can the birds manipulate it's implementation?

Many questions remain to be answered, and he scientists involved with the study stress the idea that the research is in it's infancy. They do, however, suggest that perhaps the magnetic north, to a bird wanting to migrate, would appear as a darker or lighter area in the bird's vision. This idea has been forwarded before; the concept is framed by the presence of cryptophores in the brain, which react to magnetic fields. However, some scientists also note that this isn't the end all be all of migratory investigation. Sure, if you have a compass, you'll know which way you're headed, but what if you don't have any idea where you are? Certainly, the bird's brain must also include a map of some sort to make the compass useful.

In addition to this, the experiment has yet to be replicated, and as noted in the comments, should be conducted in similar, migrating species, as well as more sedentary species. Do all birds have the ability, or just those that experience migratory restlessness? Do all birds need it? What about birds migrating south? Do they just reverse direction? The scientists did note a need to conduct the experiment on a species to species level in other articles.

Whatever the result, the real question is how all of this adds up to a bunch of birds flying North really well.


Posted by Brad Garvey(1).