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(Wood Duck/Carolina Duck)
The Wood Duck is a medium-sized, perching duck found in North America. The Wood Duck also releases waste through the cloaca; the cloaca is also used for mating between Wood Ducks. Like other birds, the wood duck uses kidneys in order excrete much of its waste. This means that Wood Ducks are ureotelic, signifying that kidneys extract waste from the bloodstream and excrete it as uric acid. Unlike other organisms, Wood Ducks do not have urinary bladders, nor do they have urethral openings. Uric acid is excreted as a semisolid with feces. Unlike mammals, Wood Ducks, along with other birds, excrete creatine rather than creatinine. Because they are aquatic, excretion for the Wood Duck is a constant struggle against the natural forces of osmosis, so it excretes much at one time rather than small amounts over time.