Excretion of several ions and water in a xerophilic parrot

Abstract

1. 1. The osmolality and concentrations of several ions were measured in supernatants of natural droppings and in ureteral urine of normally hydrated and dehydrated Galahs. 2. 2. The concentration of NH 4, K, and PO 4 could be expressed as constant fractions of urine osmolality. In dehydrated birds NH 4 “occupied” 32%, inorganic phosphate 22%, and K 14% of the “osmotic space”. The Na and Cl concentrations were low (15–20 μ-equiv/l) and not well correlated to osmolality. 3. 3. The average 24 hr excretion of water and dry matter was measured to 775 ± 53 μl/kg·hr and 126 ± 18mg/kg·hr in normally hydrated birds, and 366 ± 44 μl/kg·hr and 178 ± 21 mg/kg·hr in dehydrated birds. 4. 4. The uric acid/urate precipitate contained 39% of excreted Na, 31% of K, but only 5% of Cl. 5. 5. Birds shot in the arid interior of N.S.W. had not elevated plasma osmolality. The cloacal contents had an average osmolality of 468 mOs with a NH 4 concentration of 82 mM. They were feeding mainly on grass seeds.