Finding Home

In order to write one of the earliest Tangents columns, back in 2010, I visited a pigeon afficionado in Mirpur. The rooftop of his house housed several hundred pigeons in an elaborate system of cages. Talking with him, I learned how pigeons race. The owners drive the competing pigeons to a place far away and release them. The pigeons find their way home and the first one to arrive wins.

Humans have known the pigeon's capability for homing, but how does it do it? The mechanism is not fully understood, but it uses a combination of hints and guides including the earth's magnetic field and local landmarks.

Pigeons are not the only creatures with homing ability. Many birds migrate with changing seasons and return to the same place every year. For example, in The Homing Instinct, his book on animal migration, Bernd Heinrich discusses two sandhill cranes that spend most of the year in Texas but return to the same location in Alaska every summer in order to breed and raise families.

The homing skills of the albatross are even more remarkable. It spends most of its life on the wing, flying over oceans, but when time comes to raise a family it returns to its birth spot. This may require travelling over 1500 kilometers, but it knows how to return to that exact spot where it finds a mate and breeds.

Another example is the arctic tern, the champion of migrating birds. Every year it spends the summer months in northern latitudes and the winter months near the south pole.  By flying as much as 44,000 miles every year, it avoids winter's cold altogether. Arctic terns group together in colonies and a bird often returns to the same colony year after year.

Animals besides birds can also find their home from far away. Whales, for example, routinely swim 8000 or more kilometres every year, returning home to give birth. Some species of sea turtles mate and lay eggs on the beach. After the eggs hatch, the offspring enter the ocean and spend several years in the water, travelling thousands of kilometres. After ten or more years, when they are mature, they return to their birthplace to mate.

How do these birds and animals find their way home? This is one of the great mysteries of life and numerous experiments have been performed to find the answer. For example, European scientists found that magnets interfere with the homing ability of robins, confirming the role of the earth's magnetic field. The location and angle of the sun also guides some birds. Many birds migrate by night using star maps; some become fatally confused when the territory below them acquires bright lighting. Siberian rubythroats, migrating from Siberia to South Asia, were found to become disoriented – fatally - while flying over brightly lit-up cities in China.

But the homing mechanism is not completely understood. All we can say is that many birds and animals that leave their home and travel long distances in search of food can find their way back.

How about humans? Home provides us with a dwelling, a safe haven, and a place to raise our offspring. But could we, for example, navigate our way to our home without the help of maps or roads? What if we were blindfolded and left alone in the forest? Our cognitive and reasoning abilities are strong, but I daresay our inborn homing instincts fall short of many other creatures.

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