[Tweeters] Hummingbirds and artificial sweeteners

Rachel Lawson rwlawson at q.com
Fri Jul 18 15:59:38 PDT 2014


I have always wondered about the criteria hummingbirds use to determine what makes a nectar source worth using, including how they might react to artificial sweeteners. My daughter Clare Brown found the following article:




Stromberg, M. R. and P. B. Johnsen (1990). "Hummingbird Sweetness Preferences: Taste or Viscosity?" The Condor 92(3): 606-612.

Black-chinned Hummingbirds (Archilochus alexanderi) were offered combinations of sucrose and artificial sweeteners (saccharin, aspartame) at various concentrations and viscosity levels. Sucrose at 40% concentration was preferred over lower concentrations. Sucrose at 20% was preferred over artificial sweeteners, plain water, and low sucrose/high viscosity samples. Additions of artificial sweeteners to sucrose samples had no effect on nectar consumption and, therefore, were judged to be ineffective stimuli rather than aversive. Artificial increases in viscosity had no effects on the amount of nectar removed as long as a minimum of 15% sucrose was present. Hummingbirds responded to decreased sucrose concentrations by increasing sampling behavior at feeders; at increased sucrose levels, sampling behavior decreased. Chemosensory mechanisms rather than physical measures of viscosity are responsible for the sensory evaluation and the subsequent selection of sucrose nectars.



If anyone is interested, I will send the link to the whole paper.



Rachel Lawson

Seattle

rwlawson at q.com









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