Final answer:
Birds and reptiles possess a cloaca, which is a common body opening for the digestive, urinary, and reproductive systems.
Step-by-step explanation:
Birds and reptiles have a cloaca, which is a common receptacle for the digestive, urinary, and reproductive tracts that reabsorbs water back into the body. Instead of having separate openings for excretion like mammals, birds and reptiles excrete waste through the cloaca, which allows water to be reabsorbed. Uric acid from the kidneys is secreted into the cloaca and combined with waste from the digestive process before being expelled as urate salts along with fecal matter.