A cost-benefit model predicting threshold requirements for establishment of feeding territories in nectarivorous birds was tested by comparing 24-hour energy production of nectar with energy budgets in territorial and nonterritorial Hawaiian honeycreepers. The test was positive and demonstrated that nectar productivity was more important in determining establishment of territories than intrusion pressure and floral dispersion.

Certain Australian desert mice can survive and may gain weight on a diet of dry seed without drinking water. Urine concentrations for two of the three species studied are the highest recorded for mammals. The kidneys appear to be the major avenue of water conservation.

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