Your pet parrot does urinate, but a bird's urinary system is quite different and more complex than a mammal's. A mammal’s urinary tract produces urine that can be temporarily stored in the bladder before being excreted through the urethra. A parrot’s urinary tract produces urine and uric acid, does not have a bladder, and has a single opening for poop and pee, which are usually excreted together.
Mammalian Urinary System
The mammalian urinary system has four parts: the kidneys, ureters, bladder and urethra. The kidneys filter waste from the bloodstream, concentrate it to conserve water, and regulate blood electrolyte levels like sodium and potassium. The filtered urine is sent from the kidneys to the bladder through the ureters. The bladder stores urine until it can be excreted through the urethra.
How Mammal Kidneys Produce Waste
The mammalian kidney is made up of millions of blood-filtering nephrons. Each nephron has a round glomerulus, a long loop of Henle, and collecting tubules. The gomerulus filters particles out of the bloodstream. Waste products, such as urea, are excreted in the urine. Nutrients and electrolytes are put back into the bloodstream. The filtered blood enters the U-shaped loop of Henle, which removes water, somewhat concentrating the urine. Mammals need a lot of water in their urine to flush toxic urea from the body. The urea and other waste products leave the kidneys via the collecting tubules to the ureters.
Bird Urinary System
A bird's urinary system has three parts: kidneys, ureter and cloaca. Parrots do not have bladders or urethras. Like mammals, bird kidneys filter waste from the blood, concentrate it, and regulate electrolyte levels. But a bird’s kidneys filters out two different waste products: urea and uric acid. The ureter transports the waste to the cloaca, a small compartment that is the single opening to the urinary, intestinal and reproductive tracts. When a parrot opens the cloaca it releases waste from the urinary and intestinal tracts at the same time. The dark part of a parrot’s droppings is feces, the watery part is urine and the white part is uric acid.
How Bird Kidneys Produce Waste
Birds have two types of nephrons: a mammalian type with a glomerulus and loop of Henle, and a reptilian type with a small glomerulus and no loop of Henle. Each type of nephron produces a different waste product. The mammalian nephrons filter out urea, produce a watery urine and concentrate it by reabsorbing water in the loop of Henle. The reptilian nephrons filter out uric acid. Because uric acid is nontoxic, it does not require much water to remove it from the bloodstream and is excreted as a white paste.