Here is a print out of the same story that I posted a few minutes ago.
Jim
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BBC NEWS
Hummingbird 'uses tail to chirp'
Hummingbird in flight Hummingbird chirp
A species of hummingbird makes a chirping noise with its tail feathers, not=
its throat, a study using high-speed video has suggested.
The exact source of the noise from male Anna's hummingbirds has been the su=
bject of debate among researchers.
By using specialised footage, a team of US scientists were able to show tha=
t male hummingbirds' tail feathers vibrated during high-speed dives.
The findings appear in the Proceedings of the Royal Society B journal.
The loud chirp sound is produced by male Anna's hummingbirds (Calypte anna)=
as the birds dive towards the ground at speeds that exceed 50mph (80km/h) =
during their displays for nearby females.
Hitting the right note
The researchers, Chris Clarke and Teresa Feo from the University of Califor=
nia, Berkeley, wrote in their paper that they had gathered evidence that pu=
t an end to the uncertainty surrounding the source of the sound.
"Production of the sound was originally attributed to the tail, but a more =
recent study argued that the sound was vocal.
"We use high-speed video of diving birds, experimental manipulation on wild=
birds and laboratory experiments on individual feathers to show that the d=
ive sound is made by tail feathers," they explained.
The pair added that while bird vocalisation had received considerable atten=
tion, non-vocal or "mechanical" sounds had been "poorly described".
"A diverse array of birds apparently make mechanical sounds with their feat=
hers. Few studies have established that these sounds are non-vocal, and the=
mechanics of how these sounds are produced remain poorly studied," the sci=
entists wrote.
They said the footage revealed that the trailing vane of the birds' out-tai=
l feathers fluttered rapidly to produce the sound.
The characteristic dive caused a subtle change in the shape of these feathe=
rs to produce a loud chirping sound, the researchers noted.
"Many kinds of birds are reported to create aerodynamic sounds with their w=
ings or tail, and this model may explain a wide diversity of non-vocal soun=
ds produced by birds," they concluded.
Story from BBC NEWS:
http://news.bbc.co.uk/go/pr/fr/-/2/hi/science/nature/7216230.stm
Published: 2008/01/30 11:59:28 GMT
=A9 BBC MMVIII
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