Many people wonder why bird poop is white. The reason bird poop is the white color it is instead of brown like most other animals has to do with the fact that birds, unlike mammals do not urinate. Their kidneys excrete nitrogenous wastes in the form of uric acid. Uric acid has a low solubility with water, so it comes out as a white paste.
This excrement, as well as the output of the intestines, emerges from what is called the cloaca. The cloaca is a multi-purpose hole for birds: their wastes come out of it, they have sex by putting their cloacas together, and females lay eggs out of it.
There may be an actual use for bird poop however. Some spas use it as an ingredient in their facials. In addition to a bunch of cleansers, one spa in Hawaii includes a quarter teaspoon of dehydrated nightingale droppings.
Does it work? The owner says at first the clients are skeptical. I would be too if I was paying $200 to smear bird poop on my face. But clients seem to be happy with the results.
So, what exact is in bird poop that would make it useful for a facial? The reason it may work is that it has a high concentration of urea. This is because bird don't urinate and their poop is a mixture of pee and poop. There are certain properties that make urine a skin softening agent.
Interestingly, penguins love krill, and if they eat a lot of it, their poop turns pink!