It covers your car, the sidewalks and your mouth -- if you've ever closed your eyes, looked up and opened wide like your sister told you to -- but why is bird poop a different color than almost every other animal on Earth?

Everybody has that moment when they realize they don’t know about something that they should probably know about. Whether it’s history, language, science, or cultural phenomena, you’ve felt the stinging personal embarrassment of a moment wherein you realize there’s some common knowledge that isn’t so common. Don’t feel bad; nobody knows everything. Nobody, that is, except me and my sidekick, The Internet!

Somewhere in the world, a confused soul begs the question…

Why is Bird Poop White?

As we all hilariously learned long ago, most of the solid waste generated by animals the world over (humans included) is some shade of brown. Around the same time, we all noticed that a majority of the poop that fell from the skies was white.

And despite our instinctively curious nature, most of us merely accepted this fact without question, as if the true cause was unknowable. But there is a pretty simple reason and I believe we should all know about it by now.

Birds don’t urinate! Crazy, isn’t it? And this is why their poop ultimately emerges without hue (mostly).

Like mammals, birds’ kidneys do extract waste from the bloodstream but because birds do not pee, this extracted waste (in the form of uric acid) is combined with their poop rather than excreted separately as urea in urine (yes, urea and uric acid are actually different). And when uric acid is mixed with the more solid waste in the birds’ intestinal tract, the acid dissolves and turns the poop mostly white. So, the next time a bird poops on you, don’t sell yourself short – you actually got hit with a cocktail of poop and pee. Bully for you.

[Another fun fact: birds only have one “hole” down there. They poop out of, have sex via, and (in the case of females) lay eggs all from the same place.]

Now you know.

Photo by Leighadactyl