Do birds wee?

Asked by: Smera Ahuja, Winchester

Yes, but not like we do! Birds get rid of excess nitrogen by converting it into a paste-like substance called uric acid. This is less toxic than the urea we produce, and for good reason – unhatched chicks wouldn’t be able to tolerate the urea building up inside their shells.

Also, doing away with the need for a bladder is beneficial to birds because it reduces their load when flying. Birds have just one waste opening, the cloaca, and this is why you see the white, chalky uric acid mixed in with the dark faecal matter. Interestingly, reptiles also deal with their waste in the same way.

Read more:

• Where do birds go when they die?
• How long can a human go without peeing?

Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun facts.