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 measured amounts of sugar solution that Rufous Hummingbirds (Selasphorus rufus) removed from small (10 mi) feeders placed in successional habitat around old-growth forest. Hummingbirds showed statistically significant preferences for increasing sucrose concentrations from 20% up to, but not including 70% sucrose (by mass-volume). Height significantly affected preference under nearly all conditions. Hummingbird usually preferred elevated sources over those near the ground. In some instances there were differences in preference between test locations, possibly because of differing numbers of hummingbirds visiting sucrose sources.