Why Is Bird Poop White? (All You Need To Know)

We’ve all seen it, and maybe even cursed it, when we spot it on our car windshield or on fresh laundry drying in the backyard. White guano can be seen everywhere, scattered on sidewalks, around bird feeders, and under tree branches where flocks of pigeons or starlings gather.

But have you ever wondered what makes bird poop turn white? Well, read on as we investigate the science behind these splashes.

Unlike mammals, birds do not produce urine as a separate body fluid. Instead, their bodily waste is excreted together as uric acid, a thick, white paste-like substance with a darker, semi-solid interior.

Strictly speaking, guano itself isn’t white—in fact, it’s the urine component of guano that gives it its distinctive color. Birds do not have bladders that do the same function as mammals, and they have adapted to keep themselves as light as possible to achieve maximum flight efficiency at all times.

By excreting urine and feces at the same time, the birds do not often carry the excess weight of storing urine in liquid form.

To learn more about birds’ dropping habits, and what factors affect the color of a bird’s droppings, read on. We also looked at the superstitious idea that being pooped by a bird is a sure sign of good luck on the horizon, and whether guano poses any serious health risks.

Closeup shot of a small tern defecating on the beach

What turns bird droppings white?

A bird’s kidneys work hard to extract nitrogenous waste from their body’s blood. In humans and mammals, this waste product (urea) is dissolved and excreted in urine.

Since birds do not have separate organs for urination and defecation, all waste exits the body through an opening called the cloaca. The cloaca serves as an entrance for reproductive purposes, as well as an exit for egg production and excretion of bodily waste. The white, sticky paste that the bird pulls is uric acid, the equivalent of the bird’s urine.

Bird droppings, sometimes called guano, contain high concentrations of nitrates and ammonia. By eliminating waste in this mushy form, birds limit the amount of water they lose, which means there is less risk of dehydration because they retain the water they need to stay healthy.

Close-up of bird droppings

What bird’s poop is white?

The droppings of all birds contain some degree of white uric acid, but the rest of the droppings may also be discolored depending on the bird’s diet.

For example, birds that eat a lot of berries will excrete purple or red poop. Seed-eating birds have darker droppings because their diets contain pigment-rich foods. The feces of mainly insectivorous birds are lighter in color.

Fish-eating birds such as bald eagles or ospreys produce whiter droppings than many other predators.

Fish are more easily digested by birds than small mammals or reptiles and other prey with fur or exoskeletons that form the diet of carnivorous raptors.

So when a hawk digests a fish, there is less food waste to get rid of, which is the darker element in guano.

Juvenile golden eagle perched on a branch defecating

Is bird droppings poisonous to humans?

Bird droppings carry more than 60 different diseases, most of which are linked to parasitic infections, including ringworm, chicken mites and bedbugs.

Serious health conditions associated with exposure to bird droppings include the respiratory disease histoplasmosis, which is caused by a fungus naturally found in bird droppings.

Other risks associated with exposure to guano include salmonella, yeast infections (candidiasis and cryptococcosis), which can attack the respiratory, nervous and pulmonary systems, and St. Louis encephalitis, which can cause potentially fatal inflammation of the nervous system .

Complications are very rare and most people do not experience any health problems when exposed to bird droppings, but for people with compromised immune systems, excessive or prolonged exposure to bird droppings may pose a risk of serious illness.

Short-eared owl shitting off a pole

Is it good luck to have bird droppings on you?

While it feels quite the opposite when a bird poops on your freshly ironed jacket or locks of hair, according to superstition, a bird pooping on you is the ultimate harbinger of good luck.

The superstition is said to have originated in Russia, where many people believe that the low chance of getting shit must mean good luck. If a bird shits on your head, you’re really lucky.

According to tradition, some sailors never cleaned their boats of guano, believing that the mess would protect them at sea and bring them luck when they encountered a storm in the waves.

However, there is one common exception. If the bird poo is actually a car, then it’s no luck at all, quite the opposite in fact. Some believe that being pooped by a rook symbolizes punishment for previous bad behavior.

Superstition says bird droppings are good luck

Can bird droppings blind you?

If bird droppings get into the eyes, it may cause discomfort and itching, and it is recommended to rinse them with water as soon as possible. Health risks from contact with bird droppings are rare but can have serious consequences. Always seek medical advice if you are concerned.

Patients living or working close to bird nests have been documented to contract cryptococcal meningitis, a potentially fatal swelling of the membrane around the brain caused by fungal spores in the droppings of birds, especially pigeons.

The disease can cause vision disturbances, including partial or complete loss of vision in some cases. This is very rare, but can happen with prolonged exposure to high concentrations of feces.

Does bird droppings burn the skin?

Bird droppings are acidic and may irritate your skin if left unwashed for a long time, but are unlikely to burn you. The best advice is to wash it off as soon as possible so you will most likely not experience any long-term effects or discomfort.