Bird Items in Today's Nature

To: Birding Aus <>
Subject: Bird Items in Today's Nature
From: Laurie & Leanne Knight <>
Date: Thu, 18 Oct 2001 20:54:37 +1000

Birds fly best on a full tank

 Food and formation help birds fly efficiently.
 18 October 2001


 Swimming after a heavy meal may not be wise - but flying is
 another matter. Birds fly more efficiently when loaded with
 food, new research suggests, helping to explain how they
 can migrate thousands of kilometres without stopping1.

 And a second study has confirmed the century-old
 suspicion that birds fly in a V formation to save substantial
 amounts of energy2.

 Anders Kvist at Lund University in Sweden and his colleagues
 looked at flying efficiency in red knots, small waders that
 double in size for their annual migration from Siberia to Africa. Fully
fed, red knots flying in a wind tunnel for 6-10 hours extracted
significantly more power from each unit of food.

 This might help to explain why birds often make long non-stop flights
 even when they don't have to cross an ocean or desert, says Kvist.
"Since efficiency increases when the birds are heavy, it might not be as
bad to make long flights as people thought."

 The research flies in the face of computer predictions that birds are
less efficient when full. Says bird aerodynamics specialist Jeremy
Rayner of the University of Leeds: "It's a major advance, because it has
disproved something we've held on to for a long time."

 The finding is "extremely unexpected", agrees John Speakman
 who works on animal energy use at the University of Aberdeen. "This
 changes our whole view of migrational strategies in terms of how
 much fat birds should deposit to cross, say, the Sahara Desert."

 Understanding the relationship between food and flight might help
 ecologists to measure the impact of habitat change on migratory birds,
 Speakman says. "If you're deciding whether to flood an estuary, for
 example, this could help you make more sensible predictions about how
 it will affect birds that use the estuary as a stopover."

 It is unclear how birds increase their efficiency when migrating, Kvist
says. Puzzlingly, they don't adopt the most economical strategy at all

 Kvist speculates that when birds are breeding they may keep reserves of
 strength for sudden manoeuvres such as speeding up or swerving to avoid
 a predator.

 Pelican patterns

 Birds also conserve fuel by flying in V formations. By
 measuring heart rates, researchers in France now
 have proof that pelicans use 11-14% less energy flying
 together, even when they are not perfectly positioned
 to take advantage of the wake from those in front of

 Configured flight may create a stream of air that allows
 birds to glide longer, suggests Henri Weimerskirch, the biologist at
the National Centre of Scientific Research at Villiers en Bois, who led
the study. "If you look closely, you see that the birds at the back are
gliding more than the leader."

 People have been asking whether V formations are more efficient for
 more than 100 years, Speakman says, but no one had measured energy
 savings before. "They took a century-old problem and went to the heart
of it," he says.


    1.Kvist, A., Lindstrom, A., Green, M., Piersma, T. & Visser, G. H.
  Carrying large fuel loads during sustained bird flight is cheaper than
  expected. Nature, 413, 730 - 732, (2001).

    2.Weimerskirch, H., Martin, J., Clerquin, Y., Alexandre, P. &
Jiraskova,  S.. Energy saving in flight formation. Nature, 413, 697 -
698, (2001).
Birding-Aus is on the Web at
To unsubscribe from this mailing list, send the message
"unsubscribe birding-aus" (no quotes, no Subject line)

<Prev in Thread] Current Thread [Next in Thread>

The University of NSW School of Computer and Engineering takes no responsibility for the contents of this archive. It is purely a compilation of material sent by many people to the birding-aus mailing list. It has not been checked for accuracy nor its content verified in any way. If you wish to get material removed from the archive or have other queries about the archive e-mail Andrew Taylor at this address: andrewt@cse.unsw.EDU.AU