FIELD-STUDIES OF RUFOUS HUMMINGBIRD SUCROSE PREFERENCE - DOES SOURCE HEIGHT AFFECT TEST-RESULTS

Several environmental factors affect hummingbirds' selection of sugar sources. Using a factorial test design that included several different sucrose concentrations, source heights, and test locations, we measur ed amounts of sugar solution that Rufous Hummingbirds (Selasphorus ruf us) removed from small (10 mi) feeders placed in successional habitat around old-growth forest. Hummingbirds showed statistically significan t preferences for increasing sucrose concentrations from 20% up to, bu t not including 70% sucrose (by mass-volume). Height significantly aff ected preference under nearly all conditions. Hummingbird usually pref erred elevated sources over those near the ground. In some instances t here were differences in preference between test locations, possibly b ecause of differing numbers of hummingbirds visiting sucrose sources.