As animals go, owls are pretty awesome. I mean just look at Hedwig. There are about 200 owl species on earth, and you'll find them on every continent except Antarctica. They can be as small as the sparrow-sized elf owl, or as huge as the eagle-sized great grey, and most are nocturnal loners with broad heads, an upright stance, big front-facing eyes and gnarly talons. 

Many cultures associate owls with either wisdom or death, and although they aren't quite as bright as some other birds (like crows or ravens) the death thing might not be so far off. Because if there's one thing owls are really good at it is killing things, quietly. You might even say that they are the ninjas of the bird world, equipped with some unique adaptations  to make them experts at both hunting and getting their creep on. 

Let's start with their feathers. For example, maybe you've been out walking at some point and you heard some whooshing sound only to look up and see a bird flying overhead. Well odds are that was not an owl making that noise. Most birds have smooth, sleek primary feathers which create a noisy kind of turbulence as their wings collide with the air. And that's fine if you're a plant eating goose or say a falcon who's so fast it doesn't matter if you're prey hears you coming because they're already toast, but to a night hunting owl catching dinner is all about stealth.

So their feathers are specially adapted to reduce that air turbulence and the noise that comes with it. Intead of a smooth, stiff-leading edge an owls primary feathers look more like combs. those serrated edges actually break up the air as it hits the wings creating a bunch of smaller less-noisy disturbances in the air. And even those get muffled by a softer fringe at the trailing edge of the wing. But owls also come equipped with an extra silencer, their smaller down feathers, which absorb whatever noise is leftover.

Magic feathers are awesome and all, but probably the first thing you'll notice about an owl are their ridiculously huge, front-facing eyes, which can weigh up to 5% of their body weight. All the better to see you with. Because most owls are nocturnal, their eyes need to be good at processing whatever light is available. Sp, owl eyes have large corneas and pupils that allow extra light to enter the eye and funnel back to the image-forming retina. And, compared to many other birds, owl retinas contain more of the light-sensitive rods that help them see in low-light conditions. Plus, the forward-facing set-up lets owls to look forward with both eyes, giving them a wider range of binocular vision than most birds. It also helps them judge distance and dimensions, kind of like how humans do it.

But it is not easy to squeeze such big eyes into a comparatively small skull, so owl eyes aren't round like a typical eyeball. Instead, they're more elongated and tube-shaped. They're also fixed in their sockets by rings of bone called sclerotic rings, which means owls can't roll its eyes, and if it wants to look to the side it has to turn its entire head. 

That said, contrary to popular belief, no owl can go full Linda Blair and rotate their head all the way around, though they can rotate them three-quarters of  the way in either direction, which is still pretty impressive. I mean, imagine looking to your right by turning your head all the way to the left. It's hard to picture for good reason, because if you tried it, you'd either cut off the flow of blood to your brain and have a stroke, tear your artery, or simply snap your neck, and in any of those cases you would be dead. So, you know, don't try it. 

But how come owls can do it? Well, for starters, they have more vertebrae in their necks, 14 compared to our 7, and their head are connected to their necks by just one pivot joint, as opposed to out two. This single joint gives the bird's head much more flexibility, allowing it to pivot its head on the vertebrae column, sort of how you can pivot your body on one foot. Those neck bones also feature extra large holes-- about ten times larger than the artery that passes through them-- and probably hold air sacs that help cushion that fragile artery while the owl twists its neck, so it doesn't tear.

But in 2012, a research team from Johns Hopkins discovered that there's more to the owl neck rotation puzzle. They found that while most animals' arteries typically get smaller the farther they are from the heart an owl's main neck artery actually gets a little bigger as it nears the brain, ballooning out. those larger areas might act as reservoirs, storing a little extra blood to send to the brain when the main vessel gets temporarily blocked during more extreme neck rotations. 

So, here's to Hedwig, and all her fellow owls, master ninja birds of the night. 

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