Saline drinking and cloacal excretion of salt and water in the zebra finch.

SKADHAWCE, E., AND S. Il. BRADSHAW. Saline drinking and cloacal excretion of salt and zvater in the zebra finch. Am. J. Physiol. 227(6) : 1263-1267. 1974.-Zebra finches (‘Ihenio@ygia castanotis) from Western Australia were studied in order to investigate whether wild-caught animals were able to concentrate their urine to a higher degree than domesticated birds and whether they could drink fluids of high salinity and live without water when fed dry seeds alone. ‘The amount of 0.1-0.8 M NaCl being drunk and the osmolality and Na+, K+, and clconcentrations of the supernatants of the droppings were measured. Food intake (3.3 g/24 h) and cloaca1 discharge of water (0.8 g/24 h) were measured in the dehydrated state. Water turnover was estimated by tritiated water (HTO) dilution. Saline intake was maximal (12 ml/:24 12) at 0.3 M NaCl, but at 0.8 M NaCl ( osmolality 1,475 mosM) 0.4 ml/24 h was still being drunk. Maximal urine osmolality was 1000 mosM, 40yG greater than that in domesticated finches. Due to the high rate of metabolism, the intake of 0.8 M NaCl represents only a minor fraction of turnover of body water.