Birds Fly Faster as Flocks Get Bigger
Instead of slowing things down, more birds means speedier journeys, according to a new study out of Sweden.
While it might be easy to imagine that the more crowded a bird flock becomes, the slower the whole process must also become, the opposite turns out to be true. For the first time, it's been proven that the bigger a bird flock becomes, the faster the birds that comprise it will fly.
The discovery comes thanks to scientists from Sweden's Lund University, who took a look at the flight speed of birds in an effort to determine which factors influenced how fast they would fly.
Most of the findings didn't surprise the researchers. Expected items such as a bird's own aerodynamic properties (its weight and its wing shape), wind speed and direction, and the purpose of the flight (local food gathering vs. long trips) all indeed were factors influencing flight speed.
But the scientists observed that the size of the flock had a strong bearing on flight speed, which was not expected.
"I was surprised that it is such an important factor. It has usually been neglected in studies of bird flight," said study co-author Anders Hedenström in a statement.
Hedenström and fellow author Susanne Åkesson collected their data on Sweden's Öland Island. There they studied birds' physical characteristics, counted flock populations, and recorded their speeds during flight.
To derive the birds' in-flight speed, they used an ornithodolite, a device a bit like a telescope with a laser rangefinder that can also capture key properties of wind, including speed and direction.
No matter the species of bird (the pair studied five tern species of similar body dimensions), the duo's results showed that bigger flocks flew faster.
Why that's the case is the next question they hope to answer.
Among the theories, said the researchers, is that large flocks tend to be comprised of larger-sized birds, which move at faster speeds than smaller birds. Such flocks have an easier time taking full advantage of the turbulence behind other birds – particularly true for formation fliers such as geese. The turbulence lets them maintain higher speeds.
Hedenström's and Åkesson's findings have been published in the journal Philosophical Transactions of the Royal Society B.
VIEW PHOTOS: Impressive Bird Flying Formations
Birds in flight often arrange themselves in aerodynamically optimum positions, according to a new paper in thejournal Nature
that helps to explain how birds fly in such impressive formations. Lead researcher Steven Portugal and his colleagues focused their study on northern bald ibises, but many bird species also exhibit the amazing flight behavior. Portugal, a University of London Royal Veterinary College researcher, told Discovery News that birds could be using three things to achieve their flying precision: "(1) vision – watching the bird in flight to get all the information they need, (2) feathers – sensing the changes in pressure, wind etc. through their flight feathers, and (3) positive feedback – i.e. they just fly around and when it feels easier/better they stay in that position."
The researchers determined that birds try to find "good air," meaning airflows (not just wind, but even the air created by other flapping wings) that minimize their energy expenditure and help them to get where they plan to go. Conversely, birds avoid regions of "bad air" that could work against them.
Many birds fly in distinctive V-formations. Portugal said, "The intricate mechanisms involved in V formation flight indicate remarkable awareness and ability of birds to respond to the wing path of nearby flock-mates. Birds in V formation seem to have developed complex phasing strategies to cope with the dynamic wakes (turbulent air) produced by flapping wings."
Military planes sometimes fly in what is known as an "echelon formation," which mirrors nearly the exact same flight formation of many birds. This particular bird version is a variation of the "V," only with a rounded edge.
The U.S. Navy's famous flight demonstration squadron The Blue Angels often flies in a trademark "diamond formation" once popularized by fighter-bomber pilots. In it, the pilots maintain an 18-inch wing tip to canopy separation. Birds can fly even more tightly together.
The term "murmuration" refers to a flock of starlings. These birds can create dramatic patterns in the sky, such as this one over marshlands near Tønder, Denmark. Other small birds, such as sandpipers, may also create what look to be dazzling aerial ballets in the sky as they fly en masse.
Even birds flying very close to land can do so in remarkable unison. Here, a formation was photographed as the birds flew over the beach at Camperduin in the Netherlands.
The classic "V" formation has all sorts of variations. In this case, three separate -- yet united -- groups create an arrow-like effect in the sky.
Alfred Hitchcock's classic horror film "The Birds" included many scenes where numerous birds blanketed the sky. Up close, these starlings look small and harmless but, as a huge murmuration, their power becomes evident.
From the earliest planes to those in design today, aircraft have been modeled after birds. It's no wonder. Every inch of this sleek northern bald ibis, snapped while flying over Tuscany, adds to the bird's flying prowess. Its 53-inch wingspan and powerful, synchronized wing beats must have captivated people in the ancient world too, since ancient Egyptians and other early cultures featured the birds prominently in their artwork and legends.