Sucrose Concentration Preferences of Ruby-throated Hummingbirds


Sarah M. Zalewski
School of Science and Natural Resources
Lake Superior State University
Sault Ste. Marie MI  49783



	Abstract. Ruby-throated hummingbirds (Archilochus colubris) are the only
breeding hummingbird indigenous to eastern North America. These tiny, iridescent
green marvels are a favorite of birdwatchers of all ages. People plant special flowers
and hang artificial feeders to attract hummingbirds. The birds derive their energy from
the sucrose contained in flower nectar and artificial solutions. It has been found that
flowers offer about a 20% concentration of sucrose and suggested homemade mixes (1
part sugar to 4 parts water) offer about a 25 % concentration. Since an average
hummingbird consumes one-half its weight in sugar a day, it was hypothesized that it
would be more beneficial to the bird to choose a higher concentration of sucrose and
feed longer at its source. To test this, a control group consisting of three feeders,
identical in style, color, and sucrose concentration (25%), was observed for five days.
The number of visits to and time spent at each feeder was recorded. An ANOVA test
indicated that there was no significant difference between feeders, meaning the birds
spent about equal time at all three feeders. Next, an experimental group consisting of
two feeders containing a weak (25%) solution and one containing a strong (40%)
solution was observed for 9 days. The position of the feeder with the stronger
concentration was randomly changed daily with the other feeders to eliminate location
as a determining factor of preference. A t-test indicated a very significant difference
between time spent at the strong concentration versus the weaker concentrations. This
showed that the birds would sample from all the feeders, but would spend the most
time at the feeder containing the higher concentration of sucrose. It was concluded that
hummingbirds are not only capable of detecting differences in sucrose concentration,
but they will also select for the higher concentration.



Selected References

Stokes,	Donald and Lillian. 1989. The Hummingbird Book. Little, Brown, and Co.
New York, NY. 89 pp.

Stromberg, M. R., and P. B. Johnsen. 1990. Hummingbird sweetness preferences:
taste or viscosity? The Condor. 92:606-612.