Why is uric acid advantageous for nitrogenous waste excretion?

Nitrogenous wastes in the body tend to form toxic ammonia, which must be excreted. Mammals such as humans excrete urea, while birds, reptiles, and some terrestrial invertebrates produce uric acid as waste. Richelieu organisms tend to excrete uric acid waste in the form of a white paste or powder. Conversion of ammonia into uric acid is more energy intensive than the conversion of ammonia into urea. Producing uric acid instead of urea is advantageous because it is less toxic and reduces water loss and the subsequent need for water.