Welcome to brain stuff from how stuff works. Hey, brain stuff, it's Christian Seger. 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 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 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 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 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 urea, which we dissolve into water and excrete as urine. This takes a lot of water, which means we have to 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, 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 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. Check out the brainstuff channel on YouTube, and for more on this and thousands of other topics, visit how stuff works dot com.