What is bird poop? When fresh, it can be squiggly and has dark areas and white goo. What’s with that? Birds, different than mammals, only have one body opening for their waste. So it’s actually a combination of stool and pee – all mixed together. The stool area can be various shades of greens and browns, and even have speckles. The white parts have been believed to be uric acid which birds produce instead of urine like mammals. But scientists recently determined that conventional wisdom might be wrong. Regardless, the light-colored areas are the pee part. The combination is diverse in appearance, providing mimics opportunities to specialize in different aspects such as fresh, dry, speckled, splats, and even smears.