Do birds pee?

When it comes to excretions, birds do a two-for-one deal

Ben Hoare

Sarah McPherson

Published: March 9, 2023 at 3:48 pm

Do birds pee? In a word, no. Birds are creatures of the air and therefore need to stay as light as possible. Among their myriad adaptations to do so is the design of their excretory system.

Producing pee as well as poo, as we mammals do, means you’re going to be retaining urine (which consists of nitrogen-rich urea diluted with lots of water) in a bladder. This isn’t very helpful if you are trying to keep your weight down.

So, instead of excreting waste matter as both urine and faeces, birds (with the exception of the ostrich) ditch their waste in one go through an opening called the cloaca. They don’t have bladders, nor urethral openings.

This waste product is highly concentrated uric acid - the white paste that regularly splats all over our windows, patios and cars. It doesn’t dissolve in water easily, hence its ability to cling on like a blob of plaster.

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If humans do number ones and number twos, you could say that birds do number threes. And if three is the magic number, no wonder it's considered lucky when a bird splat lands directly in our hair.

Main image © Yaorusheng/Getty

Science writer and author, and editorial consultant, BBC Wildlife

Ben Hoare is a wildlife writer and editor, and proud to be an all-round ‘nature nerd’. He was features editor at BBC Wildlife magazine from 2008 to 2018, and after that its editorial consultant. Ben writes about seasonal natural-history highlights in every issue of the magazine, and also contributes longer conservation stories. His interviews of everyone’s hero Sir David Attenborough remain a career highlight. When not working for magazines, Ben writes illustrated natural-history books for children – the kind of books he adored looking at as a kid. Several have been international bestsellers, no doubt because his two daughters read and test everything first. Ben lives in rural Somerset, UK, with owls and dormice in the garden, and is a keen birder who spends as much time as possible exploring outdoors.

Sarah McPherson

Features editor, BBC Wildlife Magazine

Sarah is features editor for BBC Wildlife Magazine. She has been on the title for more than a decade, and in previous lives has also been the magazine’s section editor, acting deputy editor and production editor. Sarah commissions scientists, writers and photographers from across the globe, and has worked with some of the world’s most renowned wildlife experts. She also regularly writes features - on topics ranging from birding in Colombia to the plight of wildlife rangers - and other content for both the magazine and the website.

kingfisher mid poo © Yaorusheng/Getty

Jellybean49 / Getty Images