Hood, W. R., Auburn University, Auburn, USA, wrhood@auburn.edu
Dunavant, E. , Auburn University, Auburn, USA, Dept of Biological Sciences

ELETROLYTE AND WATER BALANCE IN THE RUBY-THROATED HUMMINGBIRD

The liquid diets of hummingbirds can present a physiological challenge because their kidneys display obligatory losses of electrolytes. Thus consumption of human-provided sugar-water that is free of electrolytes may leave birds in negative water balance. The goal of this study was to determine the minimal concentration of sodium and potassium required by Ruby-throated hummingbirds. Individual birds (N=21) were isolated, fed one of 4 diets with added potassium, sodium, and chloride, and were monitored for water and electrolyte balance. Birds maintained body mass on the electrolyte diets but lost mass when consuming sugar-water. Bird consuming < 5 mmol/L of potassium and < 1mmol/L of sodium displayed a net loss of these elements suggesting that these animal were in electrolyte deficit. Birds consuming 32 mmol/L of potassium and 11 mmol/L of sodium excreted excess electrolytes suggesting that requirements had been exceeded. These results indicate that sugar-water likely contributes to electrolyte and water imbalance in hummingbirds and that this problem can be resolved with relatively small supplements of sodium and potassium to artificial nectars.

Poster presentation

Session #:P01
Date: 07-27-2011

Presentation is given by student: No

Presenting authors are bolded.