View From The Shed by Shaun FInnie - CAN YOU HEAR ME AT THE BACK?

CAN YOU HEAR ME AT THE BACK?

It's a weird fact that you cannot lick your own elbow. You're probably trying to disprove it right now. Don't bother. Unless you're a contortionist, you won't manage it. If you really want to find out how elbow skin tastes, ask a friend. Just don't expect them to stay friends with you afterwards.

Another strange biological fact is that no bird has visible ears. Even a bird that you'd think of as being an anomaly in this matter, the badly named Long-Eared Owl, doesn't have ears that you can see. It has tufts of feathers that it can move a bit to indicate its mood. They also disguise its outline so that prey species don't recognise them as a hunter until it's way too late. Wise old owl, indeed, but they aren't ears. The bird's actual ears are quite a way below these tufts. They're located on the side of its head around the level of its eyes, just like ours.

You and I, along with most other mammals, have gristly cups of flesh that direct sound waves into our ear canals. These curvy external bits are called pinnae or auricles, the ear lugs behind which your parents always managed to find enough muck to grow potatoes, however much you scrubbed. I suspect there may have been some fibbing involved, especially in the root vegetable department. I never understood how pinning my ears back could ever help me to concentrate on anyone either. Surely I'd be too distracted by the sharp pain involved?

Birds obviously don't have a pinna on each side of their heads to direct the sound waves more efficiently but they can sometimes move their ear covert feathers – the ones that lay over the actual ear hole – to a similar effect. It's the same as us cupping a hand behind our ears. Every little helps, as someone once said.

Going back to owls, their ears are actually offset, one slightly higher than the other so that they can get more of a '3D' image of the sounds. Any noise will hit one ear just a little before it reaches the other. It's a miniscule difference but it's enough for the owl to have a much better judgement of which direction and distance the sound came from. Most owls also have an unusual and distinctive facial disc shape. This is possibly most recognisable to us in the strangely beautiful but concave heart-like face of a Barn Owl. While they may not have the external pinnae that we do, the shape of that face acts in a similar way, helping to direct all noises toward the ear holes. Imagine how the bowl of a satellite dish works and you're in the right area.

Once the sound gets to the ear itself, all birds hear in much the same way that we do. If I remember my O-level biology correctly that involves sound waves vibrating the ear drum, then something involving liquid and hairs inside the cochlea which in turn sends out electrical neurological impulses. The brain then translates these impulses so that we (and the birds) can understand them as 'sounds' and react appropriately. I'm sure it works something like that but I have to be honest; I failed that particular exam and the science involved wasn't that much clearer to me when I revisited it in researching this blog. If you want to know precisely how it all works, ask a biologist, or a fifteen year old who is currently studying it. Hope the exams go well, kids.

I might not fully grasp the biological engineering of it all but I do know that most birds can hear approximately the same aural range as we humans do. That means that the highest and lowest pitches that we and they can recognise are fairly similar. They can't, for example, hear a high whistle in the way that dogs can, nor the really low ultra-sound that whales use to communicate. But in some cases, especially in predators who hunt live prey for a living, birds can hear noises at a much lower volume than we ever could, and they can pinpoint the direction from which the sound is coming much more accurately too.

For example, some birds' hearing is so highly-tuned that they can hear a bug chewing away at the underside of a tree's bark layer, or an earthworm tunnelling away under the soil. That's incredibly useful if you're hunting for food that you can't necessarily see. Others can even navigate in almost total darkness using echo location in the same way that bats do. They make a stream of clicks and create a mental image of their surroundings from the sounds that bounce back to them. It's almost beyond our imagination.

So the next time you hear a Robin announcing to the world that it's survived to see another dawn, or hear a Blackbird shouting a warning call as it noisily clatters away from you, just remember that the rest of the bird world is hearing these sounds in pretty much the same way as you are. Congratulations. For just the tiniest moment you managed to enter their world.