BrainStuff Classics: Why is Bird Poop White?

Bird poop: It’s the bane of cars, statues, and occasional hapless pedestrians across the world. But what is this stuff anyway? Learn about birds' amazingly efficient waste systems (and why their waste is white) in this classic episode of BrainStuff.

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Episode Transcript

Speaker 1 (00:01):
Welcome to brain Stuff production of I Heart Radio. Hey
brain Stuff, I'm Lauren voc Obam, and I've got a
classic episode for you today from our former host, Christian Sagar.
And it's one of those gross but pressing questions about
the world around us. Why is bird poop white? Hey,

(00:22):
brain Stuff, it's Christian Sager. Today's question is pretty gross. Okay,
let's give it a go. Have you ever washed a
car just to have a bird poop on it a
few minutes later? It's sad when you think about it.
Despite the wealth of technological and social innovations across the
span of human history, we still can't stop birds from

(00:42):
flying around crapping on whatever they want anytime anywhere. A
bird actually pooped on my dog's head the other day.
And look, this is not normal poop. It's white, sometimes
with a dark spot in it. But why why is
bird poop white? Well, the answer here is it isn't.
At least, bird poop isn't all white. It's a mix

(01:05):
of colors, and it can vary with the species of
the bird or its diet, but there's definitely white stuff
in there. Right. Well, it all comes down to streamlining.
Birds are like any other animal they take in food,
process it for energy and excrete waste. However, where mammals
like deer elephants or bill murray have two different excretion

(01:25):
systems like urine and feces, bird biology ain't got time
for that. Birds don't even have separate exits for their
waste and reproductive systems. Instead of the genitalia anous combo
so popular in the mammalion world, birds have a one
stop shop called the cloaca. It's the entrance exit point

(01:47):
for the intestines, urinary tract, and reproductive system. Yep. Think
about that for a second. Birds also process the food
they eat in a different way. We mammals break down
protein and produce nitrogenous waste, but we make it into urrea,
which we dissolve into water and excrete as urine. This
takes a lot of water, which means we have to

(02:10):
drink lots of it and also means we don't do
well in places without much water. Birds take a different approach,
and one that conserves water. Instead of dissolving that waste
into urine, they primarily excrete something called uric acid. It's
a solid pasty junk that's the white stuff in a way.

(02:30):
Birds aren't just pooping on our cars, statues, buildings, and
occasionally very unlucky people looking up with their mouths open.
They're also peeing. And here's why. Remember how earlier I
mentioned this was all about streamlining. Birds aren't trying to
conserve water out of some strange sense of environmental responsibility.
They've evolved to reduce their weight and carrying all that

(02:53):
extra water around to produce urine. It just doesn't make sense.
There are also, and I can't believe I'm saying this,
pros and cons to bird poop. Pro it's a great fertilizer. Con,
it can carry a wealth of diseases. Also, it's been
used as a cosmetic of facial cleanser. True story. Well,
if it's a pro or con, that's up to you.

(03:18):
Today's episode was written by Ben Bolan and produced by
Tyler Clang. Brain Stuff is a production of iHeart Radios
How Stuff Works. For more in this and lots of
other gross but interesting topics, visit our home planet how
stuff Works dot com. Plus for more podcasts for my
heart Radio, visit the iHeart Radio app, Apple Podcasts, or
wherever you listen to your favorite shows.