Eye is in the tail of the beheld:
Male peacocks have fancy tails that they display for female peacocks.  (Pay Attention SCIENCE vol. 341 no. 6148 August 23, 2013 page 821 reviewing J. Exp. Biol. 216, 3035 (2013)) Yorzinski and others got some females to wear goggles that made it possible to know exactly what the females were looking at and then let some males do their stuff. 

The male peacock tail has long been an example of evolution run wild.  It’s size and color are thought be the result of choices made by amorous females over eons.  It has been her tastes that have dictated his appearance.  This is typical Darwin – life is basically one on one competition to have offspring, no holds barred and winner take all.  Of course some of us think that cooperation is more conspicuous than competition in life.  You can think of it as being like heavy traffic.  Every driver does whatever possible to proceed through as if the traffic weren’t there.  The first to get there has more time to work and more time to raise family so it’s good Darwin stuff.  But in fact the most conspicuous thing is how intensely everyone concentrates on everybody getting there safely.  Nine parts cooperation for maybe one part competition if that.

The results with the peahens turned up something that some may not have expected.  Peahens don’t much like those tails.  All right, at a great distance where it is all the peahen gets to see she may be attracted to a colorful male tail.  But that’s not the way it’s displayed.  The male struts his stuff from a distance of a foot or two.  The female generally doesn’t look at all or if she does she looks at his feet or the lower feathers.  That is quite in keeping with my own experience.  When I have watched males present I have found myself watching the show much more than the female; of course she may be quite bored with it.

So just for mischief’s sake, let’s propose a different scenario.  Since the female doesn’t like the tail, maybe it has another purpose.  The only other thing I know about peafowl is that they will clear an area of snakes, at least I think I read that once, so let’s go with it.  The peacock tail is part of a snake killing strategy.  Last time I saw a peacock its tail was down.  But I did notice the neck.  It’s muscular, it tapers dramatically and it’s very flexible.  All of these things should make it an excellent striker.  The snake does not taper the same way, so when a snake strikes the striking part of the body weighs about as much per inch as the launching part.  In the peacock,  and I did not dissect the bird to verify this, the launching part is heavier and stronger.  Then consider the tail.  Fanned out and seen from the front it’s quite big.  The one thing I am pretty well convinced of with snakes is that they’re not very intelligent.  The snake may recognize a threat, but most of what it sees is harmless.  The next thing about the tail is that it rustles when the peacock shakes it.  I don’t know whether a snake can hear something like that or not, but it might be a distraction.  The most conspicuous thing on the tail is the decoration, which looks like a lot of enormous eyes.  The peacock’s own eyes are rather hidden by a black stripe.  So the snake has to use its limited cleverness to figure out just which eye or eyes it needs to be concerned with. 

The final point about the tail is that when fanned its design gives a lot of air resistance.  As the peacock head strikes forward it tends to throw the body back but a little nudge from that great tail can launch the body forward, adding to the speed of the strike.  And when it is time to recover the tail lets the head and neck recoil quickly without the need for putting a foot out front and pushing, obviously not something you would like to do with a poisonous snake.

So I think an argument can be made that the tail is a part of a snake killing strategy.  And, always interested in data, I can propose how to support the idea.  Watch some peafowl with snakes.  Do the males fight snakes more often?  And when they do, do they expand their tails.

If you ever see it happen, do let me know.

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