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Birds and reptiles do not urinate; all their excrement comes out together. Because they do not excrete urine, the nitrogen in their waste is excreted as uric acid instead of urea. Uric acid is what forms the white paste that we associate with bird poop. However, if you will look closely, you'll find that there is other, darker material as well.

While our poo is generally brown because the haemoglobin (the red substance on the surface of red blood cells which makes them red & also allows them to carry oxygen to our bodies) gets broken down to a brown coloured pigment called bilirubin & is excreted in our poo.

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13y ago

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