What Dr Karl said is here:
http://www.abc.net.au/science/articles/2008/06/17/2277297.htm
"Just recently, my primary school daughter, little Lola, did a school project
on the peacock.
She made a magnificent model, and wrote an essay that included the widely-held
belief that the purpose of the splendid plumage of the male (the peacock) is to
attract the female (the peahen).
But this simple "fact" is actually a puzzle, and is almost certainly wrong.
Now the first thing to realize is that the peacock's "tail" is not actually his
tail.
His real tail feathers are quite small and nondescript. The big showy plumage
comes from feathers which are on his back, not his tail. To avoid confusion,
the bird scientists call it a "train".
The standard belief is that the peacock does his magnificent feather display
specifically to attract the female peahen.
The peacock can raise the long feathers of the train into a glorious
semicircle, about two metres across (not bad for a bird only about a metre
long).
Each brilliant metallic-green feather carries an iridescent eye. The feathers
keep growing during the autumn and winter, and molt once each year in the
summer.
The story goes that when the peacock spies a potential mate, he erects the
feathers in his train into a fan.
He then draws the fan forward and wraps himself in it, and then sends ripples
running through the feathers.
He then draws the fan further forward, and quivers it so violently that it
takes on a shimmering appearance while the feathers make a rattling sound. This
part of the courtship is called the ecstasy.
He will then manipulate the muscles at the bottom of each feather to change the
loudness of the sound, and does this about twice each second.
This is called a shiver, and a peacock keen to impress a peahen can generate up
to 20 bouts of shivering, with each bout lasting up to six minutes, or more.
The display is spectacular, and it's definitely done for the benefit of the
female peahen. But, she is not automatically won over.
Instead, she will normally perform one of three behaviours: ignore it and pass
on by; passively accept the display; or actively solicit the display.
On the surface, this seems like a classic case of sexual advertisement by the
peacock. But over the years, there have been pieces of data that don't fit in
with this simple picture.
First, the peacock often displays his train after the female has started the
courtship routine, not before.
If the Big Display is his advertisement as to how good it can get, surely he
should do a display before the female starts the courtship?
Second, over the years, there has been conflicting evidence both for and
against the link between the train display and mating success by the male.
There is not a general consensus.
And as a part of this conflict, there are still continuing arguments about what
are the most successful aspects of the train.
Would it be its length, or the diameter of the eyes in the feathers, or the
number of eyes per square metre, or the frequency of the shiver, or the
symmetry of the train, and so on? The question is far from resolved.
Fourth, the manufacture of the train is controlled by oestrogen (female)
hormones, which is very unusual for a display ornament that supposedly affects
mating success.
Testosterone (male) hormones are far more common in this arena.
Fifth, there is actually not that much difference between the trains of
peacocks across different populations of the birds. So, to a potential mate,
one peacock's plumage is as good as another's.
And finally, the quality of the train itself does not accurately reflect the
genetic and health conditions of the peacock — thus making it a false sexual
advertisement.
So that leaves us with the increasingly probable position that the glorious
train and display of the peacock is an advertisement that once might have had
significance, but is now obsolete.
In other words, the peahen is really interested in other aspects of the peacock
(perhaps his stimulating conversation) but even to qualify in the mating
stakes, he needs a pretty train.
So why does he still have this magnificent spread of plumage? Maybe, like most
males, he's his own biggest fan."
Peter Shute
________________________________________
From: On
Behalf Of Philip Veerman
Sent: Thursday, 18 February 2010 11:51 PM
To: 'Nathan'
Cc: 'Birding Aus'
Subject: Peacock coutship
Sounds like someone has got their wires crossed. That sounds
nonsensical. For one thing males court the female, not the other way
around. The female is the one who decides. Of course everything in
evolution is an accident but it is also driven by a process, so it is
not without reason. The train of a male peacock is so elaborate and the
behaviour that goes with it is so extreme that it is absurd to suggest
it is not a huge advantage to the males who grow the biggest brightest
trains. So in that way it is not an accident, it is surely driven by
female choice over the generations (it is not actually a tail, it is the
overgrown rump feathers).
Philip
-----Original Message-----
From:
On Behalf Of Nathan
Sent: Wednesday, 17 February 2010 8:55 AM
To: birding-aus
Subject: Peacock coutship
I was listening to an ol podcast of Dr Karl yesterday and he said that
the female peafowl decided whether to cout a male before she even sees
the males tail and that the tail was an 'Evolutionary Accident' I don't
doubt this as fact but I am wondering how on earth you would test that?
~Thanks
~Nathan Ruser
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