Pigeons don’t produce urea like mammals do.
Instead, their nitrogen-rich waste is either turned into guanine or uric acid.
This acid reacts with water to create a sticky white paste which gives bird poop it’s color.
The white paste is actually pigeon pee rather than poop, usually it coats the darker coloured poop.
A Pigeon’s Biology Is What Makes Their Poop White
To get to the bottom of the mystery, you have to start with the biological design of the pigeon itself.
Unlike mammals, birds have developed in such a way that they do not have separate organs for storage and removal of bodily waste.
That is, they do not have a bladder and urethra, nor a rectum and anus.
Instead, both of the bird’s waste products are removed from the body simultaneously through something called the cloaca.
The cloaca acts as the only waste exit that birds and some other kinds of vertebrate animals have.
Both male and female pigeons have cloacas (instead of penis/vagina type sexual organs), it is also from where eggs are laid.
So the mixture of both the urine and the faeces is the first factor in getting to the recognisable white poop colour, but that’s only part of the process.
Mammals, including humans, excrete their nitrogenous wastes in the form of urea (the final product is urine) but that is not quite how it happens with birds.
Instead of urea, a pigeon’s nitrogenous wastes are converted into either guanine or uric acid, and the key difference between the way that mammals convert this and birds convert this is that both uric acid and guanine is much more powerful at reducing water loss.
As a result of this extra water in the waste mix, the uric acid reacts to form a sticky white paste.
Ultimately, it is the uric acid reacted water that creates the predominantly white colour of pigeon poop, but the thing to remember is that that the white paste isn’t actually the faeces!
It’s not something we recommend doing for fun, but if you were inclined, take a closer look next time and you will find that the white part is the pigeon pee, and the darker centre is the actual poop!
Choose Your Car Colour Carefully
It’s not that humans are obsessed with bird poop, but any car driver knows that it can be difficult to remove.
If you want to reduce your risk of your car getting covered in pigeon droppings it’s not only about being careful where you park.
Would you believe the colour of your car also matters?
According to a study, red (18%) and blue (14%) cars attract the most bird poop.
These are followed by black (11%) and white (7%) with green being the least afflicted.
You can be sceptical and think it is down to there being more cars of those colours on the road, but that’s not true.
The percentages simply do not correlate according to the RAC which states that black is the most popular colour in the UK.
If you do not want your car to be a poop magnet, think carefully when choosing the colour!