Fig. 3. Effect of water and nitrogen intake on excreta. In yellow-vented bulbuls, both water and protein intake had a significant effect on the proportion of nitrogen excreted as ammonia. The proportion of nitrogen excreted as ammonia was positively correlated with water intake (A: y=0.6x+18.4, r²=0.54, F_1,18=21.3, P=0.0002). The residuals of this relationship were negatively correlated with protein intake (B: y=-0.03x+5.5, r²=0.23, F_1,18=5.4, P=0.03).