It all matters. Be it one person, one bird, or one tree. We are all connected. As John Muir wrote in My First Summer in the Sierra:

"As soon as we take one thing by itself, we find it hitched to everything else in the universe."

The sketch is Heart Lake in his beloved Sierra Nevada.

Hitched to everything else in the universe

Funny how it can take nearly 40 years to learn that something as commonplace as the stereotypical owl sound is made, not by one owl, but as a duet between the male and female tawny owls.

Also see: how owls’ necks turn so far around, or why do birds migrate so far.

The classic twit-twoo is actually a duet

Owls are famous for being able to turn their heads seemingly full circle. It turns out some owls can turn their necks an amazing 270 degrees whereas our necks turn a measly 180 or so — see if you can turn your chin along your shoulder on both sides.

However, it’s likely the cause for this amazing feat is that, unlike our eyes, theirs are set facing forward and don’t rotate. So rotating their head becomes a key skill. Biomechanically they are able to turn so far by having twice the neck vertebrae as we do. If each vertebrae turns a little then having more helps them twist much further than us.

And yet the real trick is turning your neck while maintaining blood supply to your head through the arteries that also run up your neck. Rotate too far and the arteries can twist, stretch or be impeded. Owls have evolved a number of nifty strategies to help them turn their necks while maintaining blood flow. These include having the large carotid arteries towards the centre where they twist less than ours do, which run up the sides of our vertebrae. They also have loads of space around the arteries that run up inside the vertebrae and an area that may pool with blood at the base of the skull to provide a kind of reservoir if flow gets restricted. And more. All kind of amazing.

How owls’ necks turn so far round

…regulate temperature and (maybe) to keep feathers clean while eating. Keeping the feathers clean was my inspiration for this sketchplanation - there’s something about the cold practicality of not messing up your feathers while you’re tucking into some carrion. However, it looks like it is more likely to be for the more prosaic reason of regulating temperature and keeping cool. As Dominic McCafferty, at the University of Glasgow points out:

‘…other groups of scavengers, particularly giant petrels, have feathered heads. Large mammalian scavengers also don’t have bald heads, so why vultures?’

Should you be interested, read more at the University of Glasgow’s Why do vultures have bald heads?

Sketchplanations tagged with birds