[neilep (OP)]

Outside my store today I observed a couple of happy pigeons larging it pigeon style !!...but as they walked about I noticed that their heads bopped backwards and forwards real fast !!..in empirical tradition I tried this myself and I couldn't see a bloody thing proper and it made me look silly too !!..so how can pigeons do it ?....I assume that their brain works it all out eh ?...but also and probably more fundamental is WHY do their heads bop backwards and forwards when they're walking ?



'Men are the same as women...just inside out !'

[Exodus]

Neil were you walking around pigeon stye in the shop? lol!

Don't think this is completely relavent but birds move their heads about when looking at an object in order to work out the distance as their eyes are on either side of the head, we don't have to do that as both our eyes look forward.

[neilep (OP)]

Hi Rich....well I embraced the staff to join me in some formation pigeon choreography ! []

Yes I've noticed birdies twitch their heads a lot to get an accurate view, but next time you see a pigeon, you'll notice that with each step it makes, its head thrusts back and forth quite fast....try it !!........hmm.....maybe they just like doing impressions of woodpeckers ![]

'Men are the same as women...just inside out !'

[Exodus]

If i tried it right now i might vomit!! I have a hangover from last night coupled with the feeling queezy after this mornings little boat adventure.

I'll have a butchers at the pigeons though buddy, next time i come to the shop, i expect you and the staff to be well rehearsed so you perform the pigeon dance for me!

[neilep (OP)]

...you can join in !!..and then we'll do the 'Funky Chicken'.....

'Men are the same as women...just inside out !'

[bezoar]

I always wondered how they walk and don't get motion sickness. All that head bobbing would make me nauseous.  And I do remember a parrot once cocking his head to the side and taking a good look at my arm before he bit it.

[neilep (OP)]

I'd only give your arm a little nibble Nancy !!!!.....but I need answers people !!!!!

'Men are the same as women...just inside out !'

[chris]

Good observation about pigeons Neil.

There is a very good reason why pigeons 'bob' or move their heads in the way they do when walking and it's to do with helping them to see the world as clearly as possible.

Animals, including humans, move their eyes using muscles, called extra-ocular muscles, which are inserted into the edges of their eyeballs. These muscles are under both conscious and unconscious control; so you decide what you want to look at, and the mechanics of the process are fine-tuned by some clever neural networking in the brainstem.

You can demonstrate this on yourself quite simply. Your eyes can accurately track a moving object - a process known as "smooth pursuit" - and if you watch someone's eyes 'pursuing' something you'll see that they move steadily and smoothly according to the trajectory of the thing they are watching. But try creating the same smooth movement without something to pursue - it's impossible - instead your eyes will move as a series of short jerks or 'saccades'.

As a second experiment, try looking at your finger and shaking your head from side to side. Despite the rapid movement of the head you maintain a pretty clear image of your finger in front of you. This is referred to as the vestibulo-ocular reflex - the balance organs in your inner ears (the vestibular apparatus) are compensating for your head movements by moving your eyes in the opposite direction by precisely the right amount and at precisely the right speed to keep your eyes fixed on your finger.

Now shake your finger and keep your head still. Your eyes 'keep up' with your finger, again maintaining a clear view. This is called an 'optokinetic reflex' and it is intended to keep the world stable on the retina to preserve a clear visual image. You can see a beautiful example of this if you watch passengers sitting opposite you looking out of the window of a train or bus as it comes into a station - you'll see their eyes flicking back and forth as they fixate on sequential targets, pursue then, then flick back to fixate on the next visual target. This is because, relative to your eye, a big chunk of the world (the bit you are looking at) is moving. So the eye compensates by matching its movements to the rate of movement of the visual scence to maintain acuity.

But pigeons' eyes are located on the sides of their heads and are adapted to show them a huge swathe of the visual scene - they can see an area of over 300 degrees without moving. The disadvantage of this remarkable 'surround vision' is that movements produce significant motion parallax errors - where objects nearby appear to move faster than objects further away - which can be very confusing.

As a result, to preserve visual acuity, when a pigeon walks it locks its head in position whilst moving the body beneath it. At the last possible moment, just as a pirouetting ballerina holds her head in one place to avoid becoming giddy, the pigeon thrusts its head forward to the next 'lock' position. In this way the parallax effects are minimised, enabling the pigeon to keep a bird's eye view on his world !

"I never forget a face, but in your case I'll make an exception"
 - Groucho Marx

[Exodus]

We can always rely on Christopher!

[neilep (OP)]

Clever pigeons and even clevererererererererer Christopher !!!..Thanks Chris.

'Men are the same as women...just inside out !'

[_Stefan_]

Wow, that's amazing!

[daveshorts]

I noticed this effect and had a go at videoing the movement of a pigeon's head with my high speed camera, and yes it does stay still.

http://www.thenakedscientists.com/HTML/content/kitchenscience/garage-science/exp/why-does-a-pigeons-head-bob-as-it-walks/

[graham.d]

Wow! What a great question and answer, Neil and Chris.

[neilep (OP)]

Wow...5 years in the making !..thanks Graham.d and to Chris for his answer .................and Dave for his great video !