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Why birds fly in V formation

why-birds-fly-in-v-formation

Birds migrating in V formation

One of the joys of the changing seasons is seeing migratory birds make their journey in the impressive V formation. Larger birds, like geese, pelicans, swans and cranes head south for the winter and in spring, head back north to their breeding grounds. Most birds that fly in V formation have a long journey and fly at extreme altitudes. I, for one, have always been mystified and fascinated by this aerial spectacle of nature. Why and how do they do it?

Photo Credit: Flickr: Stevencook

Every formation has a lead bird out front who leads and sets the pace for the others. The first bird has to work the hardest since it flies through undisturbed air. When the lead bird tires, it will move out of the lead position and fall back into one of the lines of the V. Another bird will rapidly move forward to take the lead position to maintain the V formation. The two birds at the end of the V tire more rapidly and rotate frequently with the rest of the flock. The birds in the middle of the formation get the most benefit.

The lead bird breaks up the wall of air that the flocks flies into and experiences the most air drag or air resistance. The resulting swirling air or eddies caused by the lead bird's movements creates a lift or upwash for the birds behind it and so forth. The tubes of circulating air called wingtip vortices are generated as the wings generate lift. One wingtip vortex trails behind the tip of each wing. Each bird positions itself in a staggered position to the bird in front of it to get the extra lift and reduced air resistance or drag. A bird flying in formation therefore expends less energy than when it is flying solo. Another reason for flying in the V formation is that each bird can observe the position and flight direction of the other birds in the flock to avoid collisions, as well as, to keep the flock together.

Illustration of wingtip vortices - A picture says a thousand words.

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This illustration shows how wingtip vortices are generated at the tip of the bird's wings. Air moves from the area of high pressure (under the wing) to the area of low pressure (top of the wing) at the tip of the wing. As the wings move through the air, this curling action causes spirals or vortices at the tips of the wings. The rising air or updraft of the vortices shedding off the bird in front will lift up the bird trailing behind it.

Migratory birds take advantage of each other's wingtip vortices by flying in a V formation so all but the leader are flying in the upwash from the wing of the bird ahead. A little upwash makes it a little easier for the bird to support its own weight. It also lowers the heart beats, increases the flying range, and conserves up to 50-70% more energy.

Producing thrust and reducing drag

In most bird species, there are 10 primary feathers along the outer edge of each wing. The primaries propel the bird through the air.

When a Canada goose flaps its wings during flight, several things happen. During the downstroke (power stroke), a wing moves downward and forward producing forward thrust. During the upstroke (recovery stroke), the tips of the primaries separate and these 'slots' allow passage of air through them which reduces friction or drag as the wing comes up.

Photo Credit:Photobucket lzphotography

When a goose is hurt or shot and falls out of formation, two of the geese will leave the flock and follow the injured geese, stay with it, nurture it until it recovers. Or in the case that the injured bird dies, the two geese will start a new formation and catch up with the flock.

why-birds-fly-in-v-formation

Snow geese (Anser caerulescens)

Almost perfect symmetry

Snow Geese breed in the Arctic Tundra and winter in farmlands, lakes and coastal areas in the American south, southwest and east coast. These attractive geese occur only in North America, and make an annual round trip journey of more than 5,000 miles at speeds of 50 mph or more. Seen in flight, adults are white with jet black wing tips. When migrating, they follow well-defined geographical features like coastlines, rivers and mountain ranges.There are four primary corridors in North America. From east to west, they are the Atlantic, Mississippi, Central and Pacific flyways.

In Asia, Bar-headed Geese (Anser indicus) regularly migrate over the Himalayan Mountains, even over Mt. Everest at an altitude of 30,750 feet (9375 m) where the air is thin and the temperatures drop to minus 60 degrees F.

Source:ChipperWoods Bird Observatory

Snow Geese Migrating in V formation - Teamwork at its best

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Photo Credit: Crappy Wildlife Photography

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These migrating snow geese are taking advantage of the aerodynamic V formation. This is one of my favorite air shows choreographed by nature. Not only is this so beautiful to behold, but it proves how natural instinct, teamwork and trust play a big part in the lives of migrating birds during their long journey to their destination.

During migration the Snow Goose flies so high it can barely be seen. They form shifting curved lines and arcs as they fly. Hunters call these birds "Wavies." The name is derived from the Chippewa name for this bird, wewe. During the summer, their heads are often stained red as a result of gathering in mud containing iron oxides.

Source: whatbird.com

"Winged Migration" video clip - Sit back and watch in awe.

"For eighty million years, birds have ruled the skies, seas and earth. They fly vast distances. Each Fall, they fly the same route back. This film is the result of four years following their amazing odysseys, in the northern hemisphere and then the south, species by species. Jacques Perrin from "Winged Migration" is one of the most respected producers in France. This film is about exploring the mystery of birds. More than 450 people, including 17 pilots and 14 cinematographers were involved in the making of this documentary."

Barnacle geese migrate to Britain and Ireland in the winter, to escape the harsher climates of Greenland and Svalbard Island. The sudden appearance of the adult geese, with no prior sign of nesting or goslings, gave rise in folklore to the story that barnacle geese either grew on trees or developed from the goose barnacles found on driftwood.

Read more about the Barnacle Goose

Ducks flying with lead bird - Lead bird is also called the point bird

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Photo Credit: Mr. rockin'P

Ducks and geese fly long distances to find the resources they need to survive and reproduce. The prompt for fall migration is not as clear but is most likely related to the timing of reproductive events and molting. Migratory departures are triggered by short-term changes in weather and habitat conditions.

Pelicans in V formation

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Photo Credit: sonicberg

The pelican is known, above all, for its incredible beak, equipped with an enormous elastic pouch, which it uses as a net to capture and transport its prey. With a capacity of 13 litres, it can hold up to 4kg of fish. Certain species have a wingspan of 3.5 m and weigh up to 13 kg.

Pelicans are excellent gliding and soaring birds and can cover long distances. They flap their wings very little and make good use of rising currents of air. They can fly up to 24 hours without stopping and cover 500 km in a day. The highest flying speed recorded is 56 km/h.

More interesting facts about the brown pelicans

Who does not love pelicans - They are cute, comical and make you smile.

Cormorants (Phalacrocorax carbo) - Known for excellent fishing skills

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Photo Credit: dekayne

Cormorants are members of the pelican family, with all four toes on each foot webbed, which helps them in swimming and chasing fish underwater.