Answer:
Uric acid is the least toxic waste than ammonia and urea which is excreted by animals. Ammonia is the most toxic waste excreted by mainly animals live in aquatic habitat like fishes because it requires lots of water to remove.
Animals that live in deserts do not have a large amount of water to remove waste so it generates a less toxic waste which their body can tolerate in higher concentrations. The process of generating uric acid is energetically very costly when compared with the generation of other nitrogenous waste.
Therefore uric acid can be excreted with very less amount of water which is helpful for animals living in dry condition, therefore, animals that live in a dry environment excrete high levels of uric acid.