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The cost of flocking

Flying in a flock comes at a considerable energetic cost for pigeons, raising the question of why they do it.

By | June 22, 2011

Pigeons landingCOURTESY OF THE STRUCTURE AND MOTION LAB, THE ROYAL VETERINARY COLLEGE

Geese glide swiftly through the air in a V-formation that provides great aerodynamic benefits, including decreased energy requirements. Pigeons, on the other hand, fly in busy cluster flocks -- taking sharp, banked turns and flapping their wings rapidly -- which, it seems, takes a great deal more energy than flying solo, according to new research published this week in Nature.

The finding suggests that pigeons, and other cluster flocking birds, fly in flocks for reasons other than energy efficiency.

"It's very interesting," said Geoff Spedding, chairman of the Department of Aerospace and Mechanical Engineering at the University of Southern California, who was not involved in the research. "As far as I know, nobody has had the instrumentation before to measure things such as wing beat frequency in flocking animals."

COURTESY OF THE STRUCTURE AND MOTION LAB, THE ROYAL VETERINARY COLLEGE

Jim Usherwood and a team at the Royal Veterinary College at the University of London tracked 18 racing pigeons during 7 flights over 2 days. The animals were equipped with mini-backpacks sporting GPS systems, accelerometers, and gyroscopes, which measure position, motions, and changes in orientation, respectively. The equipment recorded that, within a flock, the pigeons made tight, banked turns like aircrafts do, which quadrupled power requirements, and that they flapped their wings faster, also increasing energy expenditure. In fact, the closer they were to neighboring birds, the faster they flapped.

Flocking, therefore, comes at an energetic cost to pigeons, the authors concluded, and is not the reason they fly together. Because these birds are well-fed racing pigeons free to fly whenever they desire, it is possible, in this case, the birds were flying for the sake of exercise. "Presumably being a fit, good flier has all sorts of selective benefits," said Usherwood, and racing pigeons have been specifically bred to be athletic and fast.

But birds may also flock to gain the advantages of collective navigation, greater safety from predators, or for social benefits. "Energetics isn't everything," said Usherwood.

"There are probably many overlapping reasons for flocks of various kinds," said Spedding, who wrote an accompanying News & Views article in Nature. It possible that some flocks form simply as a consequence of social behavior: Some birds just tend to stay close to each other -- on the ground and in the air.

 

 

Path of a single pigeon, and relative positions of other pigeons, for a single flight. Playing at double realtime. Courtesy of Jim Usherwood, Structure and Motion Lab, The Royal Veterinary College. From thescientistllc on Vimeo.

 

J. Usherwood, et al., “Flying in a flock comes at a cost in pigeons,” Nature, 474:494-7, 2011.

 

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Comments

Avatar of: Nazmul Islam Swapno

Nazmul Islam Swapno

Posts: 1457

June 23, 2011

This is a great article. Thank you so much to share this type of nice post.

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Avatar of: Brian Hanley

Brian Hanley

Posts: 66

June 23, 2011

This is an old problem in operations research, a response to predators. Ships in wartime "flock" in convoys for the same reason. You can look it up in WWII era stuff that proved it.

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Posts: 0

June 23, 2011

This is a great article. Thank you so much to share this type of nice post.

driveway repairs

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Posts: 0

June 23, 2011

This is an old problem in operations research, a response to predators. Ships in wartime "flock" in convoys for the same reason. You can look it up in WWII era stuff that proved it.

Avatar of:

Posts: 0

June 23, 2011

This is a great article. Thank you so much to share this type of nice post.

driveway repairs

Avatar of:

Posts: 0

June 23, 2011

This is an old problem in operations research, a response to predators. Ships in wartime "flock" in convoys for the same reason. You can look it up in WWII era stuff that proved it.

Avatar of:

Posts: 0

June 26, 2011

this is really benificialy fort evry one

zanzibar

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Posts: 0

June 26, 2011

As to pigeons, there is a tall clock in Sacramento, CA around which each evening a flight of pigeons wheel, round and round. I often wondered why this particular behaviour, and so one evening I sat and watched. The wheeling continued for several minutes, then from the clock tower flew a large owl, snatched a pigeon who screamed horribly for a long time, and then when all that was over, the rest entered that same clock tower for the evening. Evidently, all that wheeling around the clock tower was some form of Russian roulette, the victim having been selected for the night, allowed the remainder to sleep in peace.

Avatar of:

Posts: 0

June 26, 2011

this is really benificialy fort evry one

zanzibar

Avatar of:

Posts: 0

June 26, 2011

As to pigeons, there is a tall clock in Sacramento, CA around which each evening a flight of pigeons wheel, round and round. I often wondered why this particular behaviour, and so one evening I sat and watched. The wheeling continued for several minutes, then from the clock tower flew a large owl, snatched a pigeon who screamed horribly for a long time, and then when all that was over, the rest entered that same clock tower for the evening. Evidently, all that wheeling around the clock tower was some form of Russian roulette, the victim having been selected for the night, allowed the remainder to sleep in peace.

Avatar of: Zanzibarhotels

Anonymous

June 26, 2011

this is really benificialy fort evry one

zanzibar

Avatar of: Edo_mcgowan

Anonymous

June 26, 2011

As to pigeons, there is a tall clock in Sacramento, CA around which each evening a flight of pigeons wheel, round and round. I often wondered why this particular behaviour, and so one evening I sat and watched. The wheeling continued for several minutes, then from the clock tower flew a large owl, snatched a pigeon who screamed horribly for a long time, and then when all that was over, the rest entered that same clock tower for the evening. Evidently, all that wheeling around the clock tower was some form of Russian roulette, the victim having been selected for the night, allowed the remainder to sleep in peace.

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