It’s 4am.
The sun hasn’t even thought about breaching the horizon.
But I’ve been awoken by an urgent desire that won’t pass.
Nature calls.
I can hear birdsong outside. The dawn chorus.
I wonder if the birds are up to pee as well?
Do birds pee? How do they pee? Why do they pee?
Questions that are so commonly thought but rarely asked.
In short, yes, birds can pee. Kind of.
This article aims to explore what bird pee really is, as well the processes behind how birds actually pee, and the differences between bird and mammalian pee. Read on to discover more.
What is Pee?
There’s never a dull moment in biology.
Who doesn’t want to learn about pee, right?
But what is it? Like, really?
In simple terms, pee, or urine, is a fluid containing water and waste products.
In many animals, pee is produced by the kidneys.
Through a variety of overly complicated processes – I’m talking glomerular filtration, tubular reabsorption and micturition (but hey, we’ll leave these to the experts) – the kidneys filter waste and extra water from the blood.
Now, to fully be considered pee, the fluid produced by the kidneys must be stored in the bladder, then expelled through the urethra.
Ah.
For any bird anatomy experts reading, a red flag may have already been raised.
Birds don’t have a bladder. Nor do they have an urethra. In fact, most birds don’t have a penis or a vagina.
So, what happens? Can birds even pee?
Now, and this may cause quite the debate, but I’m going to go ahead and say yes, birds can pee.
It’s just not pee as we mammalians know it.
Before we get into the ins and outs of bird pee, let’s briefly explore why animals have to pee.
Why Do Animals Pee?
Everything pees – from the smallest insect to the largest mammal. It’s a simple necessity of life.
But why do we pee?
The main reason life on earth has evolved to pee is to expel waste products, such as nitrogen and salts, from the body.
If animals, birds included, allow waste products to build up, a whole host of metabolic abnormalities may arise. These, in turn, could lead to long term kidney failure (for those that have kidneys, of course).
However, different animal groups have evolved different ways to expel waste products from their bodies.
Difference Between Mammalian and Bird Pee
Time to brush up on those high-school biology lessons.
Mammals
First up, we have the mammalian pee. The one we’re all so accustomed to.
We’ve established that mammalian pee is stored in the bladder.
But what really goes on inside here?
Firstly, we need to remember that pee is full of nasty toxins.
One of these toxins is ammonia.
Ammonia is formed via the breakdown of special proteins, or amino acids.
In high concentrations, ammonia is very toxic. It dissolves in the blood to form alkaline ammonium hydroxide, which disrupts our balanced blood pH. It can also affect important cell reactions that are responsible for essential tasks such as respiration and cell signaling.
In short, ammonia is not good for the mammalian body.
To get around this, ammonia is mixed with water to create the less toxic urea, where it can be stored in the bladder and then swiftly expelled from the body through the urethra.
But birds? Well, something entirely different happens there.
Birds
Now, this is where things get a bit complicated.
But bear (or should it be bird) with me.
Birds do have kidneys, but they do not have bladders or urethras.
You won’t find them cocking their legs and peeing on lampposts.
But, like mammals, birds need to remove excess nitrogen and toxins from their system. So how do they do it?
They create uric acid.
Manufactured in the liver, uric acid is a white, paste-like substance. It is a soluble substance that allows birds to conserve water.
Like mammalian pee, uric acid is a nitrogenous waste product that birds produce and excrete.
We’ll get into the ins and outs of how uric acid is excreted, but first, why do birds create uric acid and not urea, like us mammals?
Benefits of Uric Acid
Benefits to Birds
Whilst the production of uric acid is relatively costly to birds, the advantages outweigh the disadvantages.
Because uric acid is less toxic than urea and more water soluble, less water is needed to dilute it to safe levels.
This means birds are able limit water loss, especially in environments where water is hard to come by, such as desert habitats.
Carrying around a bladder full of urine could use up a lot of energy, especially for long distance migrants such as swifts. So, excreting uric acid in paste form means birds aren’t expending unnecessary energy on excess weight.
Think of it like loading a car for a big trip – the more items you put in the car, the heavier it’ll become. The heavier the car is, the more gas it’ll use, ultimately resulting in you investing more money.
Some bird species, typically long-legged birds such as storks, purposefully deposit their waste onto their own bodies.
In extreme environments, when temperatures soar, birds face the deadly risk of overheating. To prevent this, certain species have adapted to pee on themselves as a cooling mechanism. Also known as urohidrosis, the evaporating uric acid cools down the animal enough to survive the blistering heat.
Benefits of Bird Pee to Humans
Yes, that’s right.
We humans can, and have, benefited from bird pee, or, more scientifically correct, the uric acid produced by birds.
Also known as guano, humans have been collecting the excrement of seabirds for centuries.
As guano has a high nitrogen and phosphate content, it acts as a perfect fertilizer. In fact, the use of guano on crops increased agricultural production massively.
Typically, guano is collected from seabird colonies off the coasts of North and South America, as well as Africa, where large populations of cormorants, pelicans, and gannets have been recorded.
The diet of seabirds is made almost entirely of fish. A diet of predominantly fish is very calcium, nitrogen, and phosphorus heavy – and the kidneys work extra hard to expel any excess nutrients.
Is It Bird Pee Or Is It Poop?
Are you still with me?
To recap so far – birds, like mammals, have kidneys that help flush out the toxic ammonia buildup from nitrogen.
But we haven’t really explored how birds pee.
What happens to the waste uric acid?
Do birds pee and poop separately? Or is it one big mess?
Unlike mammals, birds do not have various openings for separate biological processes.
Instead, they have one multifunctional hole: the cloaca.
Common to birds, reptiles and amphibians, the cloaca serves as the only opening for the digestive, reproductive, and urinary tracts.
So that means bird pee, the white paste-like uric acid, comes out of the cloaca.
But have you ever stopped and noticed, or maybe had the privilege of being pooped on, that most of this white stuff isn’t always smooth?
More often than not bird pee is lumpy – almost a solid. Well, that’s the poop mixed in with the pee. And that’s bird droppings – a mix of pee and poop, all mixed together.
Typically, the feces are made first and then covered in uric acid. But, depending on the diet, amounts of pee and poop differ for each species.
Species with high protein diets, such as seabirds, create higher quantities of uric acid compared to birds with a high fiber diet, such as poultry.
Birds That Pee and Poop Separately?
As with most things in nature and biology, there are exceptions.
Ostriches, the largest extant bird species, release both pee and poop separately.
Although the ostrich doesn’t have a specialized bladder, scientists believe the ostrich stores urine in a cloacal chamber just inside the cloacal opening.
This chamber, much like the mammalian bladder, can expand in size to hold urine. Through expansion (along with muscle contractions), the path between the cloacal opening and the colon, where poop is stored, is blocked. This contributes to the separation of the two waste products.
Final Thoughts
Well, that took me back to my biology lessons.
Who’d have thought the world of bird pee could be so intricate?
All the takeaways you can bring to your next quiz night:
Birds have kidneys but no bladders. They do not produce a watery pee like mammals. Instead, they produce a white paste-like substance called uric acid – bird pee. Uric acid is often accompanied by feces, which are both excreted through the cloaca.
Well, unless you’re an ostrich. Those guys are just built differently.
