What Makes Bird Poop White?

And why is it so hard to wash off your car?

This audio story is brought to you by BirdNote, a partner of the National Audubon Society. BirdNote episodes air daily on public radio stations nationwide.


This is BirdNote.

Birds brighten our lives. We find joy in their songs, inspiration in their soaring flight. They connect us with nature. But sometimes birds connect us a bit too directly with nature. 

Park under the wrong tree – one where a flock of starlings or grackles comes to roost – and nature may be painted in white on your car so thickly that it takes a trip or two through the carwash just to see through the windshield again. 

Aside from helping you decide where not to park next time, this messy event raises a scientific question: Why is most of the bird poop we see white? The answer lies in the fact that birds, unlike mammals, don’t produce urine. Instead they excrete nitrogenous wastes in the form of uric acid, which emerges as a white paste. And uric acid doesn’t dissolve in water easily. Hence its ability to stick to your windshield like blobs of white plaster. 

It appears that drivers of some cars might be asking for trouble. A study in England found that red cars are most likely to be the target of bird droppings, followed by blue and black. Green was the least likely. So be careful where you park. And give that red Mustang a wide berth.

For BirdNote, I’m Michael Stein.

Producer: John Kessler

Executive Producer: Chris Peterson

Narrator: Michael Stein
Written by Bob Sundstrom
Song of Black-headed Grosbeak [126546] provided by The Macaulay Library of Natural Sounds at the Cornell Lab of Ornithology, Ithaca, New York, recorded by T.G.Sander.
Flock of European Starlings recorded by Martyn Stewart of naturesound.org

© 2014 Tune In to Nature.org   November 2017  ID#         poop-02-2012-11-26    poop-02  

Link to birds “targeting” red vehicles