Birds don’t pee. But what they do is pretty cool.

It’s true: birds don’t pee. They don’t produce urine—they don’t even have bladders. Imagine! Never having that oh-my-god bladder-bursting feeling riding the bus. Never standing in those long lines at the ladies’ room. No awkward conversations at the urinal (ladies you don’t want to know.) Wouldn’t it be wonderful? Birds have got it made in the pee-pee department—but that liberating quality has come at a bit of a cost.

See, birds have a whole different system down there. First of all, they have jettisoned a lot of the, um, equipment that we mammals take for granted. A lot of male birds don’t have penises; they don’t have urethras (pee-holes) either. It’s a one-stop, one-hole-does-it-all deal, and it’s called the cloaca. The name isn’t super important but the idea is very cool. One hole to unite them all: liquid-ish waste, poop, baby-making and laying eggs. Birds are all about efficiency. They have to be.

Take a close look. It’s for science.

So let’s get back to that liquid waste. Next time you have a close call with bird shite (my most recent encounter was getting crapped on by a hummingbird, believe it or not), you should take a moment to look at it.

I mean, maybe that idea doesn’t really excite you a lot, but trust me: if you’ve never taken a look at a bird turd you might never have noticed that it usually comes with two components: poopy bits and liquid, often white pasty bits. That white pasty stuff is what birds make instead of pee. And when that stuff comes out of a great blue heron and lands on your goretex jacket, you ain’t never gonna forget it. Don’t ask me how I know this.

Birds don’t pee—they poop out uric acid.

You and I, we have to get rid of the excess nitrogen that we eat. Birds do too. It’s a byproduct of protein, and it turns into ammonia which is actually toxic. So we mammals use our kidneys to make urea, which we end up diluting with a lot of water in our bladders. And out it comes as pee. Urine. Number One.

See, birds just can’t afford to use water that way. It’s too heavy, for starters. (Water weighs a LOT… especially if you’re a chickadee.) So birds produce uric acid instead of urea. Again, the vocabulary isn’t super important; what’s cool is the idea that the birds’ method is less toxic, so requires less water to dilute it. And less water means less weight, and less time spent looking for water sources.

But they poop. A lot.

The only drawback to the birds’ no-pee method is that it’s a bit more expensive (and by expensive we mean more energy-intensive.) It also means they crap a lot. Without a bladder to store that nitrogenous waste, they need to eliminate it pretty often. So they just let loose, about every fifteen minutes. On your car, on your head, on your driveway. They just don’t care; it’s gotta go. (Interesting nature fact: ostriches actually have bladders. Why them and nobody else? Because they’re ostriches. Ostriches are metal.)

It’s nasty stuff, but it’s not pee.

One other vexatious quality of all that uric acid? It’s a bitch to clean off your clothes and your deck chairs. Urea, the stuff you and I and your cat and dog make, is water soluble. Pee might be smelly and unpleasant, but it cleans up well. Uric acid, not so much. You’ll need a bit of baking soda and water for that. Vinegar works too.

So next time you get pooped upon by a bird, take a moment to reflect. You’re looking at a super-cool adaption to help birds stay lean, light, and drought-resistant. Birds rock.

Now it’s your turn, because I need to know: what’s the coolest bird that has ever crapped upon you? Let me know in the comments.