Excretion
The removal of waste substances from the blood by the kidneys, which form the 'excretory system', in the form of urine, which in birds is usually semi-liquid and creamy-white in colour. It is expelled with the faeces through the cloaca to form the droppings. In some birds, excretion of excess salts is also possible through the salt gland.From Peter Weaver's Birdwatcher's Dictionary
Copyright © 1981 by Peter Weaver