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’s killing things.
Quietly.
You might even say they’re the ninjas of the bird world, equipped with some unique
adaptations that 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 heard a whooshing sound,
only to look up and see a bird flying overhead.
Odds are, it wasn’t an owl making that noise.
Most birds have smooth and 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 your 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.
Instead of a smooth and stiff leading edge, an owl’s primary feathers look more like
combs.
Those serrated edges actually break up the air as it hits the wings, creating a bunch
of less-noisy, smaller 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.
That way, owls can both listen for the sound of dinner, and silently snatch it.
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 five percent 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.
So 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 front-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
an owl 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 heat 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 either way you’d be dead.
So, you know, maybe don’t try it.
But how come owls can do it?
Well, for starters, they have more vertebrae in their necks -- fourteen compared to our
seven -- and their heads are connected to their necks by just one pivot joint, as opposed
to our 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.
Still, even with extra padding and a little more room for blood vessels, if you’re turning
your head that far, those vessels are still going to end up partially blocked.
But in 2012, a research team from Johns Hopkins discovered that there’s more to the owl
neck rotation puzzle.
They found that while in 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 temporary 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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