I learned so much about birds today. The current New Scientist sheds light on their senses. They gave this example of the Great Grey Owl, with ears offset asymmetrically on the skull at 2 and 7 o’clock. The differential timing and volume allows it to pinpoint prey, even when the rodent is scurrying in tunnels under snow.
“Intriguingly, the hearing ability of birds living in temperate climes fluctuates through the year. The auditory regions of their brains grow during the breeding season, then shrink when song becomes less important. Understanding this process could provide clues to treating Alzheimer’s and other neurodegenerative diseases.”
“Another important difference between bird and human hearing occurs in the inner ear, and especially in the cochlea – the structure containing the vibration-sensitive “hearing” hairs. It is snail-shaped in humans, hence its name, whereas in birds it is banana-shaped. In both, the hair cells detect changes in pressure and transform these into electrical signals, which are interpreted as sound in the brain. Crucially, we cannot replace damaged hair cells, making deafness a scourge in older people. Birds, have no such problem: they can grow new hair cells. If we can discover the genetic basis underpinning this difference, it could give us the potential to solve a common cause of age-related hearing loss.”
But how about their vision system? New Scientist on the bird’s eye view:
“Raptors can see to distances far greater than we can. One reason for this is that the light-sensitive layer at the back of our eyes, the retina, has one fovea, a sensitive spot where the image is sharpest. Raptors, in contrast, have two foveae in each eye, which is equivalent to a camera having both a telephoto and a macro lens.”
Are you predator or prey? Eyes facing forward for the hunt, or to the side to detect inbound threats? It gets a lot more complicated than that, with differing functions for each eye. See below…
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