Why is it necessary for birds to immediately remove urine from the cloaca?

One of the adaptation of birds to flight is the secretion of very thick, concentrated uric acid. The concentration of uric acid requires special adaptive mechanisms and active kidney function. Although in the series ammonia-urea-uric acid, the latter has the least toxicity, it is still quite poisonous. In addition, this substance has osmotic properties, sucks water out of tissues, and water is a valuable resource for poultry. Therefore, to reduce its loss of acid, it is necessary to get rid of it as soon as possible. This is associated with the absence of a bladder and almost instantaneous emptying of the cloaca in birds.