A World on the Wing

Placing a small metal ring on a bird’s legs, in order to track its trajectories, is a very established ornithological practice, and is called banding. The data obtained from banding is extremely useful, and tells us a great deal about the migratory habits of different bird species. We now know, for instance, that grey-cheeked thrushes travel enormous distances, migrating from the forests of northern Alaska and Canada to South America and back every year. These birds weigh an average of just thirty grams, so this really is an incredible feat. New technology is now becoming available to monitor other groups of birds whose data is usually harder to capture, and this is enabling experts to make significant discoveries regarding the migratory feats of these fascinating creatures 

Several ground-breaking discoveries have been made about bird migration over the last twenty years, including revelations of their excellent sense of direction. Their ability to use the Earth’s magnetic field to find their bearings has always been linked to the magnetic iron crystals in their skulls. These small deposits of magnetite, however, actually play a rather marginal role, and their sense of direction is largely a result of their eyesight. If they are deprived of natural light and exposed to red light, for example, birds lose their bearings, no matter how many iron crystals are in their skull. 

Until recently, experts were completely unaware that a bird’s vision was such a determining factor in their ability to find their way, and other new and exciting discoveries about the bird world are being made every day. Yet we still have much to learn about the captivating field of ornithology.