Fig. 4. Total osmotic excretion in cloacal fluid CF (osmolality x CF volume) as a function of water flux. (A) Total osmotic excretion compared with diet concentration and the provision of supplementary water. Values are means ± 1 S.D. (N=7). (B) Total osmotic excretion was positively correlated with CF volume (note log scale), being highest on more dilute diets, when birds have higher water fluxes. Values are individual data (N=7) for the 14 diet trials with (solid circles), or without (open diamonds), supplementary water; the regression line is fitted to data from all diet trials (osmotic excretion = 0.045[CF volume+1]^0.563). The volume of CF excreted per day is given as log(ml+1) since the log of values <1 yields negative values.

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