How Do Birds Detect Danger?

I have often wondered, watching the little feathered friends in my yard, just how they detect danger from a distance in order to have time to escape before it gets to them. The more a person listens to the intricacies of a bird's songs and chatter you learn to differentiate between something that sounds like a bird singing from joy or happiness to something of an alarm tone to other birds.

Birds have an intricacy and depth to their communication. If you listen to any certain bird in your area, and you think you become accustom to the call it is generating, that same bird will generate a completely different call than the one you had been listening to all that time. You think to yourself what is this new message and what is the bird telling his or her comrades. Beyond a well developed eyesight, birds are dependant on their sense of hearing for survival. Take for example; a barn owl can hunt by sound alone, a woodpecker can hear insects under the bark of a tree. Pigeons are said to be able to detect infrasonic waves that come just prior to an earthquake.

Hearing helps birds detect and locate danger, food, water, and territory and shelter. Birds have a greater hearing range of sounds than humans do. Birds have what is called a "Syrinx" this organ unique to birds allows them the range of vocalizations they use. It is located just above the fork of the bronchial tubes and just below the trachea. The "Syrinx" could be related to a mammal's larynx in that it produces sound when air is forced through the trachea causing the membranes to vibrate. Unlike the larynx the syrinx is a lot more efficient using all the air passing through to create sound. A human by comparison only uses 2 percent of the air exhaled from their lungs.