The other day we wrote a post about the reduction in genetic diversity among commercial chicken breeds that attracted a surprising amount of informed comment (surprising to us, anyway; I think it shows more about the general knowledge of a city boy like me than anything else). So while we were on the subject of chickens (as we are so often because we write a lot about avian influenza) I thought I'd post up this remarkable YouTube video illustrating chicken head control. First a little background from the point of view of a human.
Humans also have remarkable abilities when it comes to head and eye control. There are six (extraocular) muscles that control each of our two eyes and since binocular vision depends upon both eyes peering at the same point they have to be coordinated. Moreover when you turn your head or your body but keep looking at the same point, the muscles have to coordinate precisely to keep the eyes pointing one way even though your head is pointing another (or moving in parallel when you look to the right or left). Remember these are two different kinds of movement. In convergence on a point the eyes are moving in opposite directions to each other, while in gaze to the right or left they are moving in the same direction. Four of the six muscles are aligned on a straight line (hence they are rectus muscles, numbers 2 - 5, below), while two are aligned obliquely (oblique muscles that pull the eye downward and laterally or upward and laterally, numbers 6 and 8). Here's a pic:
Source: Wikipedia entry on ocular muscles
This is all coordinated through the central nervous system, via three of the twelve cranial nerves (the 3rd, 4th and 6th; cranial nerves are nerves that come directly from the brain rather from the spinal cord). It is a very intricate and precisely coordinated system.
What does this have to do with chickens? Well chickens are amazing animals in their own right. We might think they aren't very intelligent (their brains are quite small, i.e., they are bird brains) but small or not, it is capable of some pretty remarkable feats. So without further ado, we present the amazing video of chicken head control:
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If indeed your "eyes are moving in opposite directions to each other" then you have bigger problems than that chicken with the flu.
Not at all. Whenever your eyes converge on a single point (for example directly in front of you) your right eye moves medially and so does your left eye, i.e., they move in opposite directions (the right eye to the left, the left eye to the right). On the other hand in lateral gaze (say, to the right) the left eye moves medially (to the right) and the right eye moves laterally (also to the right, i.e., in parallel). The oculomotor system must be able to coordinate both kinds of movement and also, like the chicken, keep your eyes on one spot when you move your head (that requires all the muscles to be firing in a specific proportion and sequence). Quite remarkable.
Chickens are smart at what they need to be smart at and see what they need to see - they spot the tiniest bugs on the ground and catch bugs in the air. They aren't terribly discriminating about what they announce to be a hawk but that is wise.
Because we free range a large area which has about 10 roosters (90 hens) who have divided themselves into 4 flocks we get to watch more natural chicken behavior. The pecking order can actually be circular with A picking on B who picks on C but C may pick on A. Roos often get seconds or thirds who help them maintain control. The head roo may not get as much sex as his sub roos as he is busy showing off or chasing off young unaffiliated roos or encroachers from another flock. Our banty roos sire a significant number of offspring whenever we set eggs from the free range instead of using a breed pen. Some enterprising hens hide nests from us and show up with a flock (other enterprising hens may add eggs to her hidden nest as well) - this is called "the hen stealing her nest" but of course it is us humans who steal the nest.
I am not sure why we find chickens so fascinating but I encourage anyone raising chickens to try free ranging them so you can enjoy the more natural behaviors. Electric chicken netting from companies like Kencove will eliminate dogs and other ground predators and the dangers from the sky are worth the joy of seeing chickens be themselves.
And just for fun, here is the story of a chicken who lost its head and lived. Mike the Headless Chicken
http://www.miketheheadlesschicken.org/story.php
September 10th, 1945 finds a strapping (but tender) five and a half month old Wyandotte rooster pecking through the dust of Fruita, Colorado. The unsuspecting bird had never looked so delicious as he did that, now famous, day. Clara Olsen was planning on featuring the plump chicken in the evening meal. Husband Lloyd Olsen was sent out, on a very routine mission, to prepare the designated fryer for the pan. Nothing about this task turned out to be routine. Lloyd knew his Mother in Law would be dining with them and would savor the neck. He positioned his ax precisely, estimating just the right tolerances, to leave a generous neck bone. "It was as important to Suck-Up to your Mother in Law in the 40's as it is today." A skillful blow was executed and the chicken staggered around like most freshly terminated poultry.
Then the determined bird shook off the traumatic event and never looked back. Mike (it is unclear when the famous rooster took on the name) returned to his job of being a chicken. He pecked for food and preened his feathers just like the rest of his barnyard buddies.
When Olsen found Mike the next morning, sleeping with his "head" under his wing, he decided that if Mike had that much will to live, he would figure out a way to feed and water him. With an eyedropper Mike was given grain and water. It was becoming obvious that Mike was special. A week into Mike's new life Olsen packed him up and took him 250 miles to the University of Utah in Salt Lake City . The skeptical scientists were eager to answer all the questions regarding Mike's amazing ability to survive with no head. It was determined that ax blade had missed the jugular vein and a clot had prevented Mike from bleeding to death. Although most of his head was in a jar, most of his brain stem and one ear was left on his body. Since most of a chicken's reflex actions are controlled by the brain stem Mike was able to remain quite healthy.
Frogs are remarkable in this respect too. They don't have the same neck range, but very precise rotation feedback control. As they don't roam like chickens, I wonder why.