Final answer:
In birds and reptiles, the primary component of urine is uric acid. Uric acid is water insoluble and tends to form a white paste or powder which is excreted by birds, insects, and reptiles.
Step-by-step explanation:
In birds and reptiles, the primary component of urine is uric acid. Unlike mammals, which excrete urea, birds and reptiles convert toxic ammonia into uric acid. Uric acid is water insoluble and tends to form a white paste or powder, which is excreted by birds, insects, and reptiles. Conversion of ammonia to uric acid requires more energy and is much more complex than conversion of ammonia to urea.