Birds Finding the Way Home

The ability of birds to return to a familiar place from any distance is a remarkable feat of nature. For centuries people have taken advantage of this ability in homing pigeons by using them to take messages from distant points back to familiar sites. Homing pigeons are domesticated nonmigratory birds with an instinct to return to their lofts (nesting sites) that is improved with training and by selective breeding. Training is started at short distances from the nesting site; over time, this distance is gradually increased to hundreds of miles from its loft at a completely unfamiliar location flies in the direction of home within a minute or two of its release. How does this extraordinary behavior work?

Understanding homing behavior is one of the greatest challenges to ornithologists. Fortunately, because they are able to carefully control the conditions under which the pigeons are released, researchers have been able to learn a great deal about how the birds navigate their way home.

Although homing ability has been fostered in pigeons by careful breeding and selecting of stock, it appears that training is not always necessary: Many species of wild birds perform similarly remarkable feats. One such bird is the migratory Manx Shearwater. Built like tiny albatrosses, these seabirds spend most of their lives skimming over the ocean surface far from the sight of land. They come ashore only to nest in burrows, which they dig in the ground on offshore islands in order to be safe from predators. The ease of locating and observing their nests make shearwaters ideal subjects for homing experiments.

In one such experiment, adult shearwaters taken from nesting burrows off the coast of Wales were flown thousands of miles from their nests to places in Europe and North America that were completely unfamiliar to them. Most of the birds returned to their burrows at astonishing speeds, speeds that would not have been possible had they wandered randomly or searched for the way home over a wide area. Even traveling over what to our eyes appears to be trackless ocean, these birds demonstrated that they knew the precise direction in which thy needed to go. Ornithologists believe that similar abilities are responsible for the return of small land birds to previous nesting and wintering places at the ends of long migrations.