Birds flying in V formation

Why do birds fly in a V formation?

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Birds fly in a V formation in order to conserve energy.

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Canadian geese In V formation
Canadian geese In V formation

Warm-weather lovers are saddened by the sight of migratory birds headed south in the fall and overjoyed when the birds return north in the spring. The intelligence of the birds cannot be denied. We would probably do the same if we could!

Whatever one’s preference for climate, however, all can agree that it takes an extra bit of intelligence to fly in that classic V formation. Why do the birds do it?

Efficient flying

For generations, scientists have been baffled by this ritualistic behavior, ever so common among many bird species. The theory was that flying in the V formation was primarily a method to conserve energy.

In 2011, a study was conducted using 14 captive-bred northern bald ibises fit with data loggers. The birds followed an ultralight aircraft to their wintering habitat, and the loggers recorded every position and flap of their wings.

Wild geese over water
Wild geese over water

The challenge of finding tame birds for the experiment was solved by utilizing ibises that had been part of a conservation project designed to reintroduce the nearly-extinct birds to Europe. They were trained to follow their human “foster parents,” who flew ahead in an ultralight aircraft.

The study, published in the January 15, 2014, edition of Nature, confirmed the long-held theory that one reason for the V formation was to conserve energy.

Led by ecophysiologist Steven Portugal of the Hatfield, UK, Royal University College, the experiment involved logging data for 3 days of the 36-day migrating period. Portugal analyzed a 7-minute portion of the data and concluded that the birds synchronized their positions and flapping to create the perfect aerodynamic situation.

How it works

When flying in the V formation, a bird’s flapping causes a vortex of air to roll off its wingtips, pushing the air directly behind it down. This is known as “downwash.”

Downwash and upwash in V formation
Downwash and upwash in V formation

The air to the sides and farther behind the bird gets pushed up. This is called “upwash.” When another bird enters the upwash area, this bird is lifted up and is able to conserve energy.

A somewhat similar phenomenon occurs in auto racing on superspeedways. Known as “drafting,” this technique considers the fact that the closer the cars are to one another, the less aerodynamic drag force can slow them down. They not only conserve fuel this way, but they can obtain greater speeds.

Although migrating birds aren’t so much affected by drag force, the lifting force allows them to conserve energy, as well, for their long, arduous journey.

The study also revealed that flying in the V formation is a learned behavior, not instinctive. Through trial and error, the birds seemed to learn the skills from each other.

 

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