Now that I have been thinking about this more, I should be working instead; they do rely on sight and sound more than anything else. I am not sure what they rely on more though sight or sound. I guess it is just like us; we too rely on sight and sound in our world too. I guess we are not so removed from the animal world after all.
Its just interesting to watch these little creatures that you have always been told were stupid and see that yes, at times they can be pretty scatter brained -at least in our eyes- yet you also can see how intelligent they can be. They have a very good associative learning capability as they can put two and two together very quickly. I think it only took my chickens a minute to associate the shovel with worms and grubs. Now its very difficult at times to dig a hole, as soon I bring out the shovel the birds come running and are never more than a few inches from it and thy inspect every shovel full of dirt, the shovel and the hole. There have been many times bringing up the shovel full of dirt and a chicken on top. My cockerel will get a little miffed at times because he is not as quick or as fast as some of the hens so he misses out on most of the good bugs. He is just too funny at times.
Maybe that is it; chicken inelegance is based on a high capacity for associative learning. They associate sights and sounds with safe, danger and food -which is probably a very good thing when you are pray. So I am guessing they rely on sight and sound equally, but how much of that is just inbred instinct.